Marten Miles II.

E.A..R 890 amplifier and E.A.R. 868 preamplifier with a Townshend Seismic Sink isolation platform.

Townshend Rock 7 Turntable with Helius Omega Tonearm and a London Reference cartridge. E.A.R. Acute 3 CD Player Music Hall Maverick SACD Player.

Kubala-Sosna Elation Balanced interconnects and Kubala-Sosna Emotion power cords, Harmonic Technology Pro-9 Reference speaker cables Harmonic Technology Magic Link Two and XLO Signature 3 interconnects Harmonic Technology Magic Reference 2 and XLO Signature 3 power cords.

Bybee Speaker Bullets, Marigo Labs TXi and VXi Mystery Feet for electronics PS Audio Power Plant Premier Power Conditioner.


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Positive Feedback ISSUE 68
july/august 2013


inex innovation

The A200 Linestage and A100 Amplifiers - Listening by Light

as reviewed by Michael Wechsberg with comments by Robert Levi


Most of the electronic equipment I review for PF is either tube or solid-state, but that's usually the most significant difference between the items. Inex Innovation brings something completely different to the table, a design that carries the audio signal on a beam of light. Patents protect much of the technology in this gear, so I doubt anyone else is using a similar approach. Carrying the audio signal on light photons, instead of electrons, eliminates many gremlins that infect most other audio components. On the other hand, implementing such an approach has its own challenges to protect the integrity of the music as it passes through the equipment. When I heard the Inex Innovation preamp and amp were available for PF I requested the lead on the review, even though I had never heard of the company. I have managed several photonic and fiber optics programs in my professional career, off and on, for almost 30 years, so I thought I could provide some good perspective on this unusual gear. Of course, none of my earlier work involved audio (I was working on microwave and digital transmission of signals). I didn't expect the extraordinary musical experience these components gave me over the past few weeks. In short, it takes some getting used to the operational quirks of a photonically inspired audio system, but the result is a breakthrough in audio performance for the price. The sound from these ingenious components is enormously revealing and involving, and the pieces are brilliantly engineered and built.

First, let me talk a little bit about the company. Inex Innovation is a small audio company in Northern California and has been around since 2004. It draws resources from a much larger firm in the telecommunications industry. Their first products were photonic audio cables distributed by Harmonic Technology in Southern California. These cables received very favorable reviews by Bob Levi in PF (see issue 38), but had some problems. In early 2012, Inex showed their first electronic components at CES, a preamp and amplifier together with improved photonic cables, and this year they debuted a new CD player and photonic USB cable recently at T.H.E. Show in Newport Beach. Inex Innovation products are available wherever Harmonic Technology products are sold in the U.S., and around the world. Inex manufactures all of their equipment in the US.

So what's the big deal with audio photonics as implemented by Inex? Most audiophiles today are only familiar with photonics in the form of the TOSLINK digital interface used between CD players and DACs. For various reasons, the TOSLINK interface has a reputation for spoiling the sound from discs, and is rarely referenced in audiophile circles. Inex photonics have nothing to do with TOSLINK or digital. They take high quality, hand-selected and matched laser diodes and modulate their light output (typically invisible infrared wavelengths are used) with the analog audio signal. The modulated light is carried in low-loss optical fiber, or optical waveguides to wherever they need to go. At the other end of the optical circuit Inex recovers the analog audio signal via light-sensitive photodiodes having high sensitivity and high dynamic range. We are not talking about high-power laser light guns here, but low-power laser diodes typically used in telecommunications with outputs of a few milliwatts. When I first started working in photonics in the 1980s, (also when I began to get serious about high quality audio), the best analog optical links had a dreadful 40dB or more of insertion loss, and a dynamic range (range between the noise floor and the input level where spurious signals begin to appear above the noise) of maybe 50dB at best. Such links cost $15,000 or more at the time (in 1980 dollars). Much R&D money was spent over the years by U.S. and foreign governments, and also by suppliers to the cable TV and internet providers to improve optical link components, and to reduce cost. Today it is possible to achieve 110 dB or better dynamic range for less than $1000. 

You probably know that glass fiber optics is used extensively today to carry digital Internet traffic and other digital data communications around the world. Pretty much the same technology is used to carry cable TV signals, some of which are analog instead of digital, from a central office into your neighborhood (there are some limited fiber cable deployments directly into the home—more so in some European and Asian countries than in the U.S.). Glass fiber is used because signals propagate for many miles with almost negligible loss and signal degradation. This is not true for copper cables. The fibers also weigh much less than copper cables, and do not require shielding to protect the signals from damage from electromagnetic interference. Fiber optics can also carry wide bandwidth signals (many gigahertz) over the same fiber as narrow bandwidth signals. 

It has not been obvious to apply photonics technology to audio because, in audio, signals travel only a few feet compared to many miles in the other applications for fiber. So why did Inex go down this road? First, once the audio signal is converted to light it is immune to any type of electrical interference including static electricity, radiated emissions from cell phones and microwave ovens, magnetic fields from power cords, and so on. These are all things that plague conventional audio cables and also signals inside the chassis of an audio component. One can wrap photonic cables around AC power cords without affecting the signal modulated on the fiber at all. Even the routing of signals inside the chassis of an amplifier or preamp is not critical as it is in a conventional amplifier, if the audio signal is carried in optical waveguides instead of copper wires and signal traces. Second, the audio signal travels in just one direction in a photonic cable or circuit. Electrical back-reflections due to impedance mismatch, or other effects in conventional cables, are virtually impossible (I say "virtually" because optical back-reflections are possible, but the state of the art today suppresses these by 60dB or better, which is negligible). This uni-directional performance is an inherent characteristic of photonic transmission, not just a preference as in conventional cables. If you plug a photonic cable in backwards, it won't work. Without signals going in both directions the audio signal remains pure and, as a side benefit, is also much less susceptible to vibration. Next, once the analog audio signal is converted to a light signal it can travel a long way with low loss and negligible effect on the signal. We know that in conventional cables longer lengths tend to add reactance that affects bandwidth, frequency response, and signal phase. Of course, cost is also a big deal in longer high-quality audio cables, as is size and weight. In fiber, on the other hand, signals can travel hundreds of meters with almost no effect on bandwidth or amplitude, and the cost per meter is small since most of the cost of a photonic cable is in the front and back ends (for those of you with large mansions, optical fiber is definitely the way to go). Photonic cables also have a wider bandwidth than almost all conventional cables. Inex claims a bandwidth of 30MHz, probably limited by some filtering somewhere to reduce noise power, but the optical components are undoubtedly capable of even greater bandwidth. Even 2MHz of bandwidth is a stretch for most conventional audio cables. I have not tried it, but I'm fairly certain that if you pass a 20kHz square wave into a photonic cable it will look like a square wave at the output, which won't be the case with most conventional audio cables. Whether this bandwidth advantage is important to audio or not can best be assessed in the context of the listening tests below.

Okay, so using photonics in audio has some important advantages, but what is the down side? The most significant thing to realize is that photonics replaces passive components in a conventional setup with active ones. An Inex photonic cable, for example, starts with a small solid-state amplifier/modulator that drives the laser diode. The front-end amplifier is selected to have a low noise figure in order to give the resulting optical link the lowest possible noise floor. This amplifier also has gain to compensate for some of the inherent losses in the electronic-to-optical conversion, and the modulator circuit ensures the laser sees the optimum impedance for the most efficient conversion. There is also a laser bias circuit that keeps the laser operating in its most linear range. Output from the laser is passively coupled to the optical fiber, which is passive. All of this stuff requires power, so Inex provides a separate dc power supply with each pair of cables. At the other end of the photonic cable the optical signal gets focused on a small photodiode that recovers the analog audio signal from the light. The photodiode is packaged with an impedance conversion circuit that provides a proper match to the audio circuit at the terminal end of the cable. Some of the Inex cables include an additional amplifier after the photodiode to ensure the overall cable has no insertion loss and enough current capability to drive any following electrical circuit. I'm guessing at some of these details based on general practices, as Inex rightly wants to keep the specifics under its hat. 

Anytime an active circuit substitutes for a passive one noise and linearity become concerns. For example, many audiophiles swear that passive preamps sound better than active ones, provided their systems can live without the gain and current drive an active preamp offers. As I have already mentioned, photonic devices have improved vastly over the past few decades such that the noise floor is only a few dB above that of a good electrical circuit, and the linearity provided by the latest generation of laser diodes and photodiodes is over 100dB. Noise and distortion phenomena in an analog optical link are quite a bit different than in an electrical circuit, but scientists have come to understand these differences and have devised methods to deal with them. Fortunately, Inex engineers seem to understand all this, but I can tell you from experience that this expertise is not widespread.

The proof of whether all this stuff is going to work is in the listening so let me turn my attention (finally) to the Inex Innovation equipment up for review. First, let's talk about the A100 monoblock power amplifiers. From the published literature, and from information from Inex, I've learned that the architecture of these amplifiers is fairly conventional class AB using wideband bipolar transistors. Each amplifier has a sensitivity of 1V for full output, and is rated for 80W into 8 ohms and 120W into 4 ohms across a 3dB power bandwidth of 1Hz to 1MHz. Input impedance is 30,000 ohms and the output impedance is <0.1 ohms. All the heat sinking is internal and I can report the amplifiers got only slightly warm even after hours of loud playing. The monoblocks are packaged in nicely made aluminum chassis that don't shout their presence, yet look at home with other expensive audio gear. There is only a single blue LED on the front panel indicating the amplifier is turned on. The quiescent power dissipation is quite low, so it is acceptable (and even encouraged) to keep the power on all the time. The power switch, two sets of speaker terminals for bi-wiring, AC receptacle, single-ended and balanced inputs are all on the back panel. Each amplifier weighs 33 lbs.

The monoblocks have medium power at 80W into 8 ohms, and were more than adequate with my average efficiency speakers in my room. They may be a bit underpowered for some of less efficient speaker designs out there, or if you like to listen at very high sound levels all the time. The fact that the rated power does not double into 4 ohms (the specification is 120W into 4 ohms) may or may not indicate some limitations in the power supply. I didn't open up the chassis to see what was inside, but I suspect these amplifiers use just a couple of solid-state devices per channel rather than multiple lower-power devices. This makes it easier to implement the matching required to achieve a coherent sound with low distortion, especially at low levels. With my setup the monoblocks controlled the 3 woofers in the Marten Django XL speakers firmly, with extended lows and good transient snap.

Inex is proud of its patent-pending amplitude-DC-filter technology used for the power supply in the amplifier. They call this technology I-Pure, and it attempts to strip out all the low-level noise and RFI coming from the AC line before it gets into the amplifier circuits. They do this with an amplitude filter, not a frequency filter. The same technology is used in the preamplifier.

Another unique feature of the Inex amplifier is that it includes a separate internal power supply that powers one end of an Inex photonic cable. The back panel contains a power receptacle for this dc supply that also uses the I-Pure technology. In fact, when you buy a pair of the Inex monoblocks, the price includes a 5m pair of Inex photonic cables. My pair came with balanced cables, but single-ended versions can be ordered instead. From the information on the Inex web site, these cables alone cost $2800 to $3200! Apart from the cable power supply, there is no photonic circuitry inside the amplifier, and it is possible to use these amplifiers with conventional cables, but Inex clearly feels that the performance will be best with their photonic cables. They provide a generous cable length of 5m (longer cables up to 10m can be ordered if necessary) so you can locate the amps close to the speakers and use short speaker cables. 

inex amplifier and preamplier

The Inex A200 preamplifier has much more of a photonic focus than the monoblocks. From the outside it looks like a handsome, high-quality, conventional line stage. The aluminum chassis is the same size and appearance as the monoblock, but the front panel sports an illuminated display on the left, a bank of 5 small push buttons and LED lights that select among the 4 inputs and mute, and another array of small push buttons on the far right used to adjust volume and balance. On the rear panel are jacks for 2 pairs of single-ended inputs, 2 pairs of balanced inputs, 2 pairs of single-ended outputs, and 1 pair of balanced outputs. Notably, there are no jacks for a tape loop or a phono stage. The rear panel also accommodates the AC receptacle and the power rocker switch. The preamp comes with a nice hefty aluminum remote control that duplicates the source selection, volume, and balance buttons on the front panel. It also has a button to dim the display through four levels, but the display does not turn off. One complaint I have is that the buttons on both the remote and preamp front panel are labeled with very small lettering etched into the aluminum. These are impossible to read in anything but bright light, so you have to memorize the button pattern. The selected input is displayed in the LCD display in fairly large numerals. Specifications for the preamp include an astounding bandwidth of 4Hz to 30MHz, maximum output of 2.5V for a 2.5V input single-ended, and 5.0V output for 5.0V input balanced. The chassis weighs 16 lbs.

The inside of the Inex preamp is quite different from any other line stage I know of, and several patents cover its architecture (I did not open either the preamp or amps to look inside). Each input is immediately converted to a photonic signal, as I've described above, and all the signal manipulation inside the preamp is done photonically inside the box. This includes source selection, volume control, and balance. Inex uses optical switches for source selection instead of electronic or mechanical switches as in conventional preamps. Immediately after the source selection function, the optical signal is applied to an amazing variable optical attenuator for each channel. The attenuator has 100 positions selected by a stepper motor that can be heard operating each time the volume up or down button is tapped. I mentioned the volume/balance pad has five buttons. The center button selects whether a single press of the volume button will cover ten increments, five increments, or one increment. Inex does not assign a specific dB or voltage increment level, but the adjustment scale is linear so one increment is on the order of 1% of the volume, which is a very fine adjustment. When the unit is first turned on the volume is always set to zero with a default increment of ten as indicated on the LCD display. This allows the user to rapidly move up to a listenable volume level of between 40 and 50 in my case. Then, switching to a smaller increment with the center button allows for finer volume adjustments. This approach provides very precise and repeatable control of the volume. The balance control is a similar optical controller, but is linked to the volume level. If the volume is up at say 60, and the increment is set to ten, then one press of either left or right balance button adjusts the balance by an increment of six (i.e., 10% of 60). If the volume level were at 30, then adjusting the balance by one push changes the increment by three (i.e., 10% of 30). Since the balance increment can be changed to 1% instead of 10%, this approach provides very fine adjustment of balance, especially at low volume. The volume and balance adjustment is very precise and repeatable, and made possible only by the use of optical devices rather than electronic ones. It took me some time to become accustomed to the adjustments, and the explanation in the manual is not very good, but before long I became comfortable with the adjustments, and found the control precision very useful. It is disconcerting to hear the stepper motors operating, as they are very audible, and this is not mentioned in the manual. However, the motors are not in the signal path and, in fact, the optical signal path is completely continuous inside the preamp and is impervious to the noise pollution that besets most other preamps. I should mention that Inex uses the same I-Pure amplitude filter technology in the power supplies for the preamp as used in the monoblocks. After all the switching and volume and balance adjustments, the optical signal is converted back to an electrical one and is applied to the output jacks. Thus, the Inex preamp can be used just like a conventional preamp as it is compatible in signal level and connectors with every other preamp out there, but inside it is working in a completely different way. Alternatively, the preamp could be the center of an entirely photonic system between the source and speakers if one were to use photonic cables as supplied by Inex and Harmonic Technology.


I was given the Inex A200 preamp and a pair of A100 monoblocks for this review. I also was supplied with the 5m balanced photonic cables that come standard with the monoblocks, and one of the I-Pure power supply boxes to power the cable. In addition, Harmonic Technology gave me a pair of their Fantasy AC10 SE power cords to run the monoblocks. I used my own Harmonic Technology Magic Reference power cord to run the preamp (seems to work like "magic" on preamps). Harmonic Technology also provided me with a 2m single-ended Photon Link cable and another I-Pure power supply so I could try out a complete photonic system. Because of the additional power supplies for the photonic links quite a few outlets are needed to get all of this stuff going. I plugged the two optical cable power supplies directly into my dedicated AC line using the stock AC cords they come with. Everything else got plugged into a WyWires Power Broker AC box, also in for review. The Power Broker was plugged into my AC line using the 12-foot WyWires cord that is fixed to it. As sources I used my E.A.R. Acute 3 CD player and my Townshend Rock 7 Turntable with the London Reference cartridge. When the turntable was in use, the E.A.R. 868 was used as a phono preamp plugged into the Inex preamp via the E.A.R.'s tape out jacks. Part way through the evaluation period Harmonic Technology loaned me one of their Magic Horizon Reference Power cords that I used on the CD player in place of the Kubala-Sosna Emotion power cord I normally use. Speakers were the Marten Django XL with Kubala-Sosna Emotion speaker cables and Bybee Speaker Bullets.

photon cable

Initially, I decided that I wanted to listen to the A200 preamp by itself in my system, to get a handle on its sound before adding the monoblocks. I normally use balanced K-S Elation interconnects between the Acute 3 CD player and my E.A.R. 868 preamp. When I used these interconnects on the Inex preamp, something was not right. There may have been an incompatibility in how the XLR connectors are wired between the two components. I next tried using the Inex single-ended photonic cables between the CD player and Inex preamp. This worked great. The preamp was connected to my reference E.A.R. 890 amplifier via K-S Elation balanced interconnects. These balanced cables worked fine. This configuration resulted in two changes to my reference setup instead of just one; the preamp and the CD-to-preamp interconnect. 

photon cable

Okay, here is the first of several bits of advice to come. When photonic gear is used, do not just plug everything in, put on a disc, and sit down and listen. You will be sorely disappointed. The active photonic devices take time to come to thermal equilibrium, and before that the sound is mediocre. Inex told me an hour or two of warm-up should be enough, but Jim Wang of Harmonic Technology said to wait 24 hours with power applied before serious listening. I found that the sound was okay for background listening in 10 minutes, and fairly decent in 30 minutes. For most purposes an hour of warm up is just fine. Photonics resembles tubes in this respect—they need to warm up. The sound was pristine in 24 hours. I played the equipment off and on for about a week before listening seriously; to allow for the normal break-in for passive components.

My initial impression using the Inex preamp and interconnect inserted into my reference system, I was hearing almost the same very fine sound I was accustomed to hearing from my reference. Bold and brassy when necessary, tender and sweet at all the right moments, and always coherent, fast, and inviting. The most significant change was in the upper-midrange and highs. Here the sound became a little drier and less fulsome, but the highs were distinctly clearer and more detailed. This was a very promising start. 

Next, I completely removed the E.A.R. 890 amplifier and the K-S interconnect, and substituted the Inex A100 monoblocks and balanced photonic cables, turned everything on again, and waited a full day. Time for another bit of important advice. Many audiophiles have become accustomed to swapping out interconnects and cables while the equipment remains switched on, maybe just lowering the volume or switching to another input. This is usually contrary to advice in the equipment manuals. I was cautioned by Inex this custom may cause genuine damage when photonic cables are being used. Because the cables are active instead of passive large pops are possible if the cables are pulled out when equipment is on. Also, it is easy to forget that the photonic cable for the monoblock gets its power directly from the amplifier via the built-in supply. The photonic cables should be powered down by turning off the monoblock amp and the separate power supply before making any changes. Unfortunately this may mean you have to wait awhile for everything to warm up again before listening seriously. But once everything is set, changing interconnects should not be necessary.

So now I had a system consisting of my reference speakers, CD and LP sources, but with all Inex photonic components in between. The first thing I noticed was how quiet things were. My all-tube reference system is acceptably quiet, but some noise is audible from the 890 amp if I get up close to the speakers, which have average efficiency. With the many active photonic components now in the system, all potential noise sources, I was concerned about the audibility of noise coming through the speakers. I can report that Inex has done a magnificent job of banishing noise from their system of components. I heard absolutely no noise even with my ear an inch from the midrange and tweeter. Worth noting is the monoblocks have 27dB of gain, so any noise downstream from them gets amplified by that amount.

A second concern was the dynamic range capability of all the photonics now in the system, and the compatibility of photonics with the remaining electronics. Within the preamp the Inex engineers have control of dynamic range margins, and can adjust the performance by proper choice of photonic components (varying factors such as laser diode power, photodiode sensitivity, electronic amplifier gain, and others). However, there is less control at the interface between the preamp and the source components since every user may have something different. Inex can customize their photonic cables to match an output between 1.0V and 5.0V. The single-ended cable I received for use in this review was designed for a maximum output of 2.5V. So, here is another bit of advice that applies uniquely to the photonic components. Make sure to discuss the output capabilities of source components, such as CD players, DACs, or phono preamps with the dealer so the correct photonics are inserted. I had just one incident during the month or so I spent listening to the Inex gear. I was playing one of Keith Johnson's Reference Recordings on CD through the Acute 3 player. Reference Recordings are known to take advantage of the full dynamic range capability of the CD medium. I had the volume control on the player cranked all the way up, and this was going into the Inex preamp via the single-ended photonic cable. Jim Wang from Harmonic Technology, distributor for Inex, was at my home at the time, and during a couple of crescendos in this recording we heard the right channel drop out briefly. Jim Wang concluded that the Acute 3, which has a 5V output capability, was overdriving the cable that has a 2.5V maximum. The easy fix was to turn down the volume control on the Acute, but it might be wiser to substitute a photonic cable with a higher maximum. Until this maximum was hit there was no hint of increased distortion or discomfort from the photonics during passages just a little bit lower in dynamics on this or any other recordings I tried. 

Let me focus now on the sound of these components. The overall sound from this photonically based system is glorious! It ranks among the best electronics I have ever tried in my home, and may be as good as the best solid-state gear I have ever heard. It's been a while since I've reviewed what I consider to be really excellent electronics from the likes of Concert Fidelity and Luxman, but this Inex gear is as good or better (and less expensive). I have not had a chance to listen carefully to some of the multi-kilobuck gear you read about in the high-end print magazines, but from my sampling at audio shows I don't believe Inex suffers much, if at all. Compared to my tubed reference system, the Inex equipment sounds a bit different, but just as revealing and involving.

The first word that came to my mind when I started listening to the Inex system was "transparent." I found this equipment to be both very revealing of everything contained on the recording, and also revealing of any sonic signature imposed by front-end source components. For example, as I was using a tubed CD player I found the sound to be very close to what I normally hear from this player in my reference system. Namely, a very fast, coherent and nimble sound with great texture, fulsome mid-bass, and spot-on tonality. I didn't try another CD player, but I did try some computer files (played through the Acute 3) with similar results. Perhaps more interesting was my experience with LPs. To play vinyl I had to insert my regular E.A.R. 868 preamp to act as a phono stage and this required an interconnect from the E.A.R. tape outputs to the Inex. Too bad I didn't have another photonic interconnect! I ended up trying four different conventional cables before finding one (Kubala-Sosna Emotion) that gave me a top-notch sound, at least as good as what I was hearing from CD. The Inex gear was very revealing of the sonic signature introduced by each cable, and it demanded the use of a fine interconnect. I'm sure had I experimented, it would be similarly revealing of VTA, tracking force, or cartridge changes.

I believe the transparent nature of the Inex gear is due to the elimination of the common artifacts introduced by cables and signal routing problems in most conventional gear. Things that affect the sound like EMI, magnetic fields, reflections, mismatches, etc. At the same time, the Inex equipment has an extremely flat frequency response that extends well beyond the audible frequency range. Some writers call equipment like this "analytic," but that implies it has a dry and etched character. The Inex equipment is more like a chameleon. It takes on the characteristics of the equipment in front of it, and passes it through with little alteration.

Compared to my reference, the mid-bass was slightly suppressed, but I expect this was a signature of the cables I was using in the reference rather than the Inex gear. The highs were very clear and transparent with terrific sparkle on cymbals, high hats, and bells (sounded great on CDs, even better on vinyl). Here I think the sound was benefitting from the very wide bandwidth of the Inex equipment. The mid-band had very good texture and tonality. The sound was slightly on the dry side, but I'm used to listening to tubes, generally warmer and more liquid. I was very pleased with the sound on everything I listened to, especially vocals and piano and large-scale orchestra. On smaller scale music the sound was very delicate and emerged from a dead quiet background. Music through the Inex gear was very involving even at very low levels (the precision volume control on the preamp is really useful when playing at low volume levels). The Inex equipment excelled in macro dynamics and pace, and was equally impressive in micro dynamics and revealing details. 

I was also very pleased with the soundstaging capabilities of both components. Despite the multiple conversions between electrical and optical signals, the correct phasing relationships were maintained, producing a very wide soundstage with realistic layered depth when such was captured in the recording. I was able to get an unusually good sense of the recording venue on most recordings, and it was illuminating to hear the reverberation die off at the end of some well-made classical recordings. Also notable was the stability of images within the soundstage. With some equipment, instruments will seem to move around as they play over their range or as the number of instruments increases or decreases with time. With the Inex gear, everything seemed to stay put. I believe this is indicative of a good low-distortion, low noise design where phase has been preserved through the entire signal chain, and also where erstwhile cable effects such as noise mixing, reflections, and frequency response anomalies have been minimized. You can tell that overall I was very impressed by the sound of the Inex equipment. My fellow PF reviewer Robert Levi spent an afternoon at my home listening to the Inex setup, and has added his impressions of the sound to the bottom of this review.


Analog photonics works for audio! Audio systems normally involve several changes in state. For example, in vinyl playback the mechanical motion of the cartridge in the record groove is translated into an electrical signal. Then that electrical signal is converted back into mechanical motion in the loudspeaker. We normally think these points, where mechanical/electrical conversion takes place, are the weak points in the system, although not everyone would agree. The electrical stages are supposed to be the easiest ones, but we have seen there are many nuances involved that can affect the sound in both good and bad ways. Inex has introduced yet another signal conversion, this one from electrical to optical and back. This would give most audiophiles pause, and for good reason, as it has taken decades to get a good handle on a different conversion process, analog-to-digital conversion for audio. This was supposed to be "perfect" back in the early 1980s. Yet, I believe the Inex implementation of the photonic preamplifier, and cables in particular, is quite brilliant and leverages mature technology developed for the telecommunications industry over the last 40 years. Their approach banishes some of the key problems that prevent our audio systems from sounding like the real thing, and rapidly catapults Inex into the upper echelons of very fine audio electronic suppliers, and at a reasonably affordable price. I find myself wishing Inex had an option for a continuous signal chain, with just one electrical-to-optical and one optical-to-electrical conversion. In the current implementation several such conversions take place. I hope more audio enthusiasts take the trouble to seek out and listen to the Inex gear at their audio dealers and then buy the system for use in their homes. I believe they will be rewarded with a wonderful sound experience listening by light! Very highly recommended. Michael Wechsberg

Additional Comments on the Inex Innovation Preamplifier and Amplifier
by Robert H. Levi

I want to thank Michael Wechsberg for allowing me to give my two-cents worth about the new Inex products I enjoyed at his home. These second generation fully photon connected pieces are the real deal. After playing my favorite CDs and LPs, my impressions are as follows:

Though solid-state gear is often quieter, with blacker backgrounds than tube gear, the Inex system is the black hole of Calcutta. There was more noise from my breathing than was apparent with the Inex. This quietude simultaneously made front of stage instruments pop, and rear stage instruments move deeper than deep into the rear of the stage.

The overall sound quality was neutral to slightly warm. The overall presentation was easily moved to warmer or cooler by a cable swap, or a different power cord. I did not detect any solid-state etch or crispness. These are truly smooth sounding pieces with a hard to pin down sonic signature, which is ideal. Listening for hours on end, they are a treat for the ears.

I have had plenty of experience with photon cables, and the early versions were a bit lumpy and bass heavy. This 2013 version, after 10 years of development, is as flat as any copper wire around. No more batteries, thankfully, as everything plugs into the wall. There were no compatibility issues, whatsoever, utilizing an E.A.R. Acute 3 CD Player and E.A.R. 868 preamp/phono [both tubes] as sources.

I was mightily impressed with how different each CD and LP sounded on the Inex system. The level of definition, the precision of the imaging, sound stage width and depth, and total lack of extraneous noise and grit were outstanding. If these pieces were cost no object, I would be satisfied with their performance, and I am a tube guy! 

The swagger and drive of the Inex amps was very similar to ultra powerful, super heavy, solid-state gear, or huge, very refined tube behemoths. They are neither. With a very reasonable size, very slick fit, finish, and design, the Inex amps perform exquisitely. No other way to put this folks: the Inex amp and preamp are breakthrough, 21st Century innovations that perform way, way beyond their weight class. With numerous patents, no one else has anything like these to offer.

Michael filled you in on the high tech side of Inex, and the why of their sound and design. As for me, I just like listening to them and imagining a live performance in the room.

If you are looking for an amp and preamp (best as a pair) that performs brilliantly, is solid-state, and will be just as extraordinary 10 or 15 years from now, look no further. Audition these Inex jewels for yourself. They are truly musical gems! RHL

A100 Monoblock Power Amplifier
Retail: $14,000/pair (includes 5m photonic cable)

A200 Linestage Preamp
Retail: $12,500

Inex Innovation, Inc.
428 McCormick Street
San Leandro, CA 94577-1005
(510) 567-8700
[email protected]

Harmonic Technology