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Positive Feedback ISSUE 3
october/november 2002


marsh sound design

A450M monoblock amplifiers

as reviewed by Mark Katz, Art Shapiro, and Dave Clark


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JMLabs Mezzo Utopias and Tannoy 12" Monitor Gold speakers in Lockwood studio cabinets (second system).

Kora Cosmos monoblock amplifiers and Eclipse preamplifier. Custom 300B monobloc SE amplifiers and Loesch-Wiesner line stage preamplifier (second system).

CEC TL-1 transport and Kora Hermes (latest version modified by Audio Magic). McIntosh MR-78 tuner. Cal Audio Icon Powerboss HDCD CD player, Luxman T117 tuner, Nakamichi 680 ZX cassette (second system).

Marigo Reference 3 digital interconnect. Tiff, Yamamura, and Marigo Gen II power cords. Kimber 8TC shotgun speaker cables and Goertz Triode interconnects.

API Power Wedge 116 Mk II for sources. Amps are plugged into a dedicated 20 amplifier line.


one.jpg (6551 bytes)These are BIG amps. It took two people to carry them into my house, one at a time. Luckily, each of these 80-lb.-plus amplifiers sports a pair of extra handles on the rear. They were placed where my Kora Triodes had stood, behind the JMLabs Mezzo Utopias. My first impression was that they were elegant looking, in a high-tech, industrial way. The silver-colored front panel has large, angled handles and a circular, backlit standby switch. The on/off switch is on the back panel, near the two sets of binding posts. Seven-foot, hardwired Monster AC cables supplied power. The amps are straightforward enough that a few minutes of examination will allow operation.

After warming up the Kora Hermes DAC and Eclipse preamplifier, the amplifiers went on. The sound was powerful, but thin and uninvolving. Within an hour, however, the character of the amps started to emerge. The first thing I heard was their sense of ease and clean, powerful bass. On the Rutter Requiem CD (Reference Recordings RR-57), the deep pedal notes of the organ were strong and well defined. The massed choral voices blended nicely and the solo soprano was very intelligible. The amps never seemed to run out of steam.

One of the amps’ strengths is their rendition of piano. On Earl Wild Plays His Transcriptions of Gershwin (Chesky CD32), the clarity of the portrayal allowed me to hear all the inner detail of the fast piano runs on "There’s A Boat Dat’s Leavin’ Soon for New York" and the variations of "Someone to Watch Over Me." Some amps can blur this, but not the Marsh. Also, the left hand had excellent heft, a relative weakness of my Kora Triodes.

One of my favorite CDs for human voice is the Bach Secular Cantatas, Volume 1 (Dorian 90199). The Coffee Cantata, a light-hearted story of a young woman addicted to coffee and her despairing father, starts with the tenor (Hugues Saint-Gelais) introducing the piece, then the baritone father (Kevin McMillan) lamenting his daughter’s coffee proclivity, and finally the daughter, soprano Dorothea Roschmann, devising a plan to get a husband and all the coffee she wants. A harpsichord, flute, and orchestra in the background keep counterpoint. Again, I heard power and clarity. The voices were always cleanly rendered, with none of the hashiness or sterility that is sometimes seen in lesser amps. Neither was the sound dull or recessed, another approach that some amplifier makers use to get a more "tube like" character.

Did I now have perfection from a pair of hefty and expensive solid state amplifiers? Out went the Marsh monoblocks and in went my 100-watt, class A triode Koras. As they warmed up, I heard what I love about these amps, the harmonic complexity of the midrange and the sweet, subtle treble that sparkled on the right hand of the piano and the flute and soprano of the Coffee Cantata. In this, they seemed superior to the Marsh amps. The Marshes offered a sense of unlimited power, ease of presentation, bass heft, and midrange clarity that let me more easily hear detailed piano runs and the majesty of a pipe organ, while the Koras helped me revel in the textures of musical instruments and human voice.

I was fortunate enough to be able to also hear the Marsh A450Ms in Art Shapiro’s system, driving his ESP Concert Grands instead of his usual Music Reference RM-9 II. The treble was more similar, but the same essential differences were evident. The bass became better defined, with great heft across the spectrum. I preferred the midrange texture I heard with the tube amplifier to the smooth clarity of the solid state. Each sounded "right" in its own way, but had a different take on the music.

I can recommend these amps if you can benefit from their high power. Despite their muscle, they have excellent clarity and treble extension with smoothness, as well as bass definition and heft. My personal preference still lies with the tube amps, whose strengths seem to better match my own listening criteria. Nevertheless, I will miss the incredible ease the Marsh A450M monoblocks lent to the music. Mark Katz





ESP Concert Grand and REL Stadium II subwoofer.

Convergent Audio SL1 Signature preamplifier and Music Reference RM9 Mk II amplifier.

VPI HW-19 IV turntable, Graham 1.5 arm, and Grado Master Reference cartridge. Wadia WT3200 transport and Kora Hermes DAC.

Nordost Silver Shadow digital interconnect. Monster Sigma 2000 interconnects and Cardas Golden Hex 5C biwired speaker cables. Tiff, Marigo and MIT Z II power cords.

Power Wedge 116 and dedicated AC lines.


two.jpg (6646 bytes)When I was offered the opportunity to review the Marsh A450M monoblock amps, I was warned that they were big and heavy. Some folks are masters of understatement. They are unusually large, and felt like a good ninety pounds per. Massive faceplates contribute to the approved-audiophile look. Front and rear handles—the former aesthetically angular—made manipulation by two people feasible, though not trivial. Alas for me, getting them out of my car trunk single-handedly was challenging. Where’s an Olympic weightlifter when one needs him? I placed them on the floor between my speakers, and it should be noted that one of my family members took an instant liking to the amps before I could even get the speaker cables installed.

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Examination of the rear of the amps revealed heavy-gauge, non-detachable cords and solid, high quality input jacks. The big knurled binding posts, two pairs per side, allowed a good grip on my spade lugs, although I would have preferred the ability to use a wrench. The posts caused some difficulty, as ridges built into them forced vertical installation of the spade lugs. My Cardas cables are far too massive to mount in the center. Consequently I had to come from above, which forced the upper lead to be scrunched into a configuration it really didn’t appreciate, and I believe I caused some damage to the cables as a result. If the jacks could be turned ninety degrees, or if the guides were eliminated, my tenure with the Marsh amps would have been more pleasant. The banana-terminated control leads for my Rel subwoofer were much more conveniently pushed into the banana connections of these jacks. I used my silver Luminous Synchestra interconnects, as my normal Monster Sigma 2K cables would not reach from the CAT preamplifier to the floor. I plugged one amplifier into each of my two dedicated power lines, with the Brickwall filter into which all other components are plugged occupying the second half of one of these lines.

Powering up the system for the first time resulted in substantial hum, with no obvious cause. I plugged both amplifiers into the same outlet, and the hum reduced considerably. It was audible a couple of feet away, but not at my listening couch. Routine manipulation of interconnects and power cords had no effect. This level of hum seemed constant until the last couple of days I had the amps, whereupon it mysteriously vanished. I can’t explain it, but was happy to know it was gone. Then another strange problem surfaced. I’ve never had any trouble with the Luminous Synchestra cables, but touching one of them at the amplifier end consistently cased a massive burst of noise, followed by the complete shutdown of that amp. After a couple of times, well aware that my speakers could never be repaired if a driver were to be blown, I pulled out the Luminous cables and replaced them with Van den Hul D102s, an older but well-regarded product. I used the Van den Huls without incident, but should make it clear that they are not a normal cable in my system.

I had every reason to suspect that these big amps would be unsatisfactory in my system, as my ESP Concert Grand speakers have proven to be quite hostile toward solid state amps. They seem to be at their worst with high-current amps. More traditional solid state amps do better, if not exceptionally so, and tube amps consistently result in excellent sound. I also discovered that, despite their relatively high efficiency–something like 93 or 94 dB according to the designer–the more power I threw at them, the better they sounded. I settled upon the 100-watt Music Reference RM9 Mark II, although I have dreams of throwing more wattage at the speakers when funds permit. Opportunities to periodically audition powerful tube amps, such as the very rare and appropriately exorbitant E.A.R. 200-watt monoblocks, proved that this is exactly what the speakers need.

Thus I had little expectation of the Marsh product being a good match, while being aware that the huge wattage of the amps–something like 900 wpc into my 4-ohm speakers–might contradict that expectation and prove an asset. My weeks with the Marsh amplifiers were quite interesting. I certainly could not use adjectives such as "dull," "uninvolving," or "lifeless" to describe the system with the Marshes in place. First of all, the low-end response of my system was a joy. It did not seem that it went any lower than with my normal amplifier, but the bottom end was more effortless, well-defined, and tonal. The realities of swapping speaker cables and interconnects made A/B comparisons impossible, forcing me to listen to several selections at a time before switching amplifiers. Normally I would prefer to go back and forth on the same music between amplifiers. Nevertheless, I had the consistent impression that the monster Marsh products were producing a higher quality of bass. This was illustrated on such reviewing standards as Bela Fleck’s Flight of the Cosmic Hippo and the ultra-low organ pedal notes on the John Rutter Requiem on Reference Recordings. There is a certain joy to limitless power!

On the other hand, there were definite shortcomings with respect to the midrange with the Marsh amplifiers, which seemed to conform to the stereotype of solid state vs. tube reproduction. Especially in the midrange, there was a consistent loss of subtlety, articulation, and ambience. The differences were not so gross as to preclude listening pleasure, but they were readily apparent, especially when going back to the RM9 from the Marshes. As an example, consider the marvelous Earl Wild piano recital, The Romantic Master, on Sony. The piano was never quite as lush with the Marshes, especially in the middle registers. The gorgeous resonance and subtlety of the huge concert grand was a bit more black and white, losing some of the tonal nuance. On the other hand, this led to very clearly articulated runs and figurations. In Mr. Wild’s jaw-dropping performance of the Tchaikovsky/Papst Sleeping Beauty Paraphrase, there was excellent impact to the savagely hit treble notes–clarity without harshness–as well as crystal-clear runs over the entirety of the keyboard. Treble chords were quite melodic. Through the RM9, the midrange and up had a beautiful, singing tone. The Marsh treble was just a tad more brittle, albeit within the bounds of reason and taste. I finally decided that it was a matter of nuance vs. assertiveness. In the savagely violent opening minute of this work, the hard-hit treble notes were not as piercing or forceful with my amplifier, and were somewhat rounder in tone. Still, through the RM9 I was more able to appreciate why this is one of the great piano recordings of all time. The treble runs seemed to tell more of a story through the tube amplifier.

Moving away from the piano repertoire, I pulled out an EMI recording of the Sibelius Violin Concerto featuring Nigel Kennedy. When the soloist came in for the first time, following a relatively prolonged orchestral introduction, I found the violin to be somewhat steelier and less musical through the Marshes, especially in the midrange. While the upper registers of the violin were honestly portrayed, the RM9 seemed to be subtler and to provide better ambience and resolution. On the positive side, this rather lackluster orchestral recording was somewhat more incisive through the Marshes. Additionally, the lower strings, which give some of the essential musical character to this dark, brooding work, were more pronounced. I appreciated this, as it gave a better foundation to the melodies. And through the Marshes, I noticed a very pianissimo kettledrum roll that had never previously registered on my consciousness–quite a surprise!

I then turned to one of my favorite vocal references: a Swedish Society CD entitled Solveig’s Sang on the Swedish Society label featuring soprano Solveig Faringer. On the title piece by Edward Grieg, there was an appealing intensity to her voice through the Marsh amplifiers, with solid piano accompaniment. True to form, upon returning to the RM9, the piano became a bit more melodic but less assertive, while the voice gained some subtlety. Another CD I often mention is a solo harp recital, Récital de harpe with Isabelle Moretti on the Harmonia Mundi label. I invariably turn to the impossibly finger-twisting finale, the Germaine Tailleferre Sonata pour harpe. Through the Marsh amps, there was less shimmer to the harp notes, typifying the diminished subtlety through these amplifiers. On the other hand, there was an improved sense of power, a desirable difference, as the concert harp is a surprisingly forceful instrument.

Additional pieces reviewed during my tenure with these amplifiers did not reveal any additional differences that might prove illustrative. Through the RM9, there was always greater subtlety and resolution, while through the Marsh amplifiers I always experienced an improved sense of power and projection. When the transportation department, aka Frank, finally arrived to haul away the monoblocks, we both listened to some of these pieces and then auditioned some music that Frank had brought. These discs were completely foreign to me. We played a CD entitled Chillin’ by David "Fathead" Newman. We played it first through the Marshes, and upon switching to the RM9, Frank seemed to light up almost at the first note. While the sax was less aggressive through the RM9–and it is, after all, an assertive instrument–we were both instantly aware of more musicality. The double bass had a more melodic, round sonority, but somewhat less definition compared to the powerhouse monoblocks. Finally, we played a Milton Nascimento CD entitled Nascimento. The Marsh gave a nicely powerful portrayal, which we could appreciate, while on the other hand sacrificing a bit in the overall sonics. I felt that both the vocalist and all of the instruments were somewhat flatter when compared to the RM9.

Much as I appreciated the ability of the Marsh amplifiers to control and impart a wonderful sense of power to my system, the RM9 had to be judged the product of choice, due to what might be summed up in that vague term, "musicality." Again stressing that my speakers are known to be tube-friendly, perhaps the Marshes will prove more synergistic in other systems. I was happy to return to my RM9, but will look back with some fondness at the huge power capacity that my speakers really enjoyed. Art Shapiro

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Reimer Speaker Systems Tetons (with the Hi-Vi Isodynamic Planar tweeters and series crossovers).

Clayton Audio M100 monoblock amplifiers. E.A.R. 834P phono stage. Blue Circle BC3000 preamplifier w/Tunsgram tubes and BCG3.1 power supply.

EAD T-1000 transport and EVS Millenium II DAC. Audient Audit and Tactic. Taddeo Digital Antidote Two (latest active version). Transrotor 25/25/60 Leonardo turntable with a Clearaudio Virtuoso wood MM cartridge. Sony RCD-W1 and Magnum Dynalab MD-90 tuner. Sennheiser HD540 headphones and Audio Alchemy headphone amplifier.

JPS Superconductor+ and Silver Sonic Revelation interconnects, and NC speaker cables. JPS digital cable. Sahuaro Slipstream and Slipstream XP (digital and Taddeo), Blue Circle BC63 (preamplifier and phonostage), and JPS Kaptovator AC cables (amps and Stealths).

Two Audio Magic Stealth Power Purifiers (one for analog, except BC3000 preamp, and a Digital unit for the digital sources), Blue Circle BC86 Noise Hound (amplifier circuit) and Audio Prism QuietLines (throughout the house). Dedicated 20 (amps) and 15 amplifier (everything else) AC circuits. Tons of Shakti Stones and On-Lines and Original Cable Jackets (frig's AC and on DSL phone line). Various Marigo VTS Dots used extensively throughout the system and room (window behind listening seat). Echo Buster acoustical treatments and Shakti Hallographs. BDR cones and board, Blue Circle Cones, DH Jumbo cones, Vibrapods, Mondo racks and stands, and Townshend Audio 2D (speakers) and 3D Seismic Sinks (CD player and preamp). Walker Audio Ultimate High Definition Links. Various hard woods placed here and there along with numerous Peter Belt treatments.


three.jpg (8484 bytes)The Marsh A450M amplifiers qualify as true statement products. They are at the top of the Marsh product line, not only in power but also in size and price. But as statement products, one thing separates them from the usual suspects, is that they are not that expensive. Okay, $10K is a lot of money, but compared to other manufacturers’ statement products, this is small change. With the Marsh AM450s, even though they won't require a second on the house, you get a lot for your $10K. These amplifiers are built like tanks, and feature styling and a circuit design that, while reflective of the price, are not the sole reasons for it being so reasonable. See these are made over seas, meaning that if they were made here in the States, the price would probably be two-fold! So consider them a bargain. Hey, even the Cary 306/200 at $5k is made overseas! Talk about another bargain!

Using some of the best parts, though not necessarily the best parts (I would think that Richard Marsh would fall into the Tim de Paravicini mantra, where a proper circuit design overshadows the contributions of designer parts and such, which is not to suggest the best parts don't hurt, just that one needs to get it right at the beginning!), these are very beautiful amplifiers. Warning! These amplifiers take a few days to sound their best, so leave them on. Right out of the box (these came already ran-in with several hundred hours) they sound terrible. After a few days things really started to gel. I situated the amplifiers on my stands and other than the use of the attached Monster AC cable, used the same Shakti'd cable set-up. Oh, too heavy for Aurios, though I wouldn't be surprised if the amplifiers sounded fine as is sitting on their stock feet.

Okay, but most important are the questions; "Do the Marsh A450Ms put the goods on the table?" and, "Are they better than my Clayton M100s?" In some respects, yes, but whether the differences mean that one amplifier is "better" than the other is up to the listener. I could live with either amplifier, but in absolute terms the Marsh A450Ms are better because they have more power–450W into 8 ohms, 800W into 4 ohms, and 1000W into 2 ohms. The Clayton M100s are distinctly handicapped at 100W into 8 ohms or 200W into 4 ohms.

Back in Issue 1 of Positive Feedback Online I reviewed the McIntosh MC352 amplifier ( which also had more power than the M100s. In the review I noted that the issue of more power was not one to sneeze at. Of course it has to be "good" power as opposed to just tons of watts. In the case of the MC352 its power simply allowed it to run a few necks ahead of the Clayton (350W into 8, 4, or 2 ohms courtesy of the autoformers). In terms of the monster M450s then the power rating becomes one of, "How good is a gazillion watts?"

Which means what? Which means that the Marsh was really, no make that REALLY fun and impressive to listen to. Music was released into the room with such force and power that any sense of restraint was lost in the transmission. Carol’s initial response was that the Marsh M450s did for her what the Blue Circle BC3.1 preamplifier had done when she first heard it in our system. And that was a serious case of WOW factor. Power and effortlessness were to a degree that we heard much from our speakers that the M100s could only suggest. Holly cow this is fun!

What did this mean to me as a music lover? Or as an audiophile?

As a music lover, it meant that I found myself wanting to play as much music as I could, which is not the norm. The A450Ms drew me away from the daily tasks of life. They were a not so subtle distraction! The weeds grew taller, the furniture got dustier, the PF website became stagnant, and I think I forgot to feed the dog.

As an audiophile, it meant that the A450Ms were as effortless as one can get without entering into the SET/horn arena. This is not to suggest that the AM450s/Reimers sounded like a SET/horn setup. Far from it! Not the least bit soft or euphonic, the A450Ms are very extended from the top to bottom, with bass that is as good as I have ever heard from my system—rock solid, powerful, and very deep (until I inserted the Cary 306/200 which allowed us to get the best the Marsh and Clayton amplifiers have to offer). Articulation and bass definition is to a degree that I would be hard to find fault. One could clearly feel or see through one’s imagination the bass strings being struck or the textures that define the subterranean region of music. Drums were as believable as you can get from a recording. With music that features percussion and synthesizers—DJ Cheb I Sabbah, State of Bengal, Badawi, Tabla Beat Science, any Bill Laswell release, and few dozen more—the sound had such impact and power that things just rocked! It was almost like the musicians were here, or I was there.

The highs offered a decent amount of airiness, without a hint of grit or etch. The treble was also as clean and articulate as a school marm on the first day of class. Cymbals and bells came across as "real" as I can recall from living with a musician many years ago. The midrange was very neutral and balanced. Neither warm nor cold, the A450M was in the middle of the yin/yang scale that so many audio writers like to use. If you are after something warm, lush, or full, look elsewhere. The A450Ms will never be mistaken for a tube amplifier or one of class A pedigree. On the other hand, while they are very revealing and detailed, they are not analytical tools that dissect every last note of the music. They represent the best that solid state class A/B design has to offer. They are fast, like a Formula One racecar, and will deliver your music with such visceral presence that you had better use a seatbelt. Dynamics were unrestricted, but with my speakers. I was not too surprised (remember my Reimers are 94dB @ 8 ohms—so they presented the amplifiers with an easy load, meaning that they were just idling much of the time).

But is that all there is? Are we only after a fast, transparent amplifier with an enormous power reserve that adds nothing to the music? Gee, ... uh, "Yes!" But, here's the crux. As good as the A450Ms are, I still preferred the M100s. See, the Marshes add no "color" or "seasoning" to the music, whereas the Claytons add just enough so that images have just that touch more palpability and presence. They also have a bit more of the euphonic "lushness" that adds a ever-so subtle sense of flesh to the bone. And they are a bit darker and warmer. The Marshes may not be cold or sterile, but the Claytons win out in musical terms, at least for me. I like my coffee with a bit of cream and sugar—whereas the Marsh are black and strong. Even so, the Marsh A450Ms are highly recommended, but only if this is what you are after. And I think that speaks for the majority of us out there. These are about as good as it gets! Dave Clark




A450M amplifiers
Retail $10,000 pair

Marsh Sound Design
TEL: 415. 927. 4672
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