Positive Feedback Logo

Violectric HPA V550 PRO Headphone Amplifier

05-01-2021 | By John Hoffman | Issue 115

Headphones and the personal audio scene are a healthy and vibrant niche in our hobby, with a growth curve that has exponentially accelerated over the past decade. The selection of headphones, headphone amplifiers, and specialty cabling manufacturers is impressive, with a width and breadth of companies that is on par with any other sector in audio. For the casual audiophile it may be difficult to understand how fundamentally different the design parameters are for a quality headphone amp. Headphones are not miniaturized versions of home speakers, and the demands on the amplifier are fundamentally different because of these unique requirements. With home audio speakers the expected impedance range is typically between 4 and 8 ohms. With previous generations of professional headphones, you would expect to see an impedance load higher than 100 ohms, with some cans scaling up to 600 ohms. In general, low impedance headphones were intended for use with portable devices, as the efficiency of these designs were desirable due to the limited power output of portable listening devices or smart phones. Designers and engineers are constantly refining their products, and lower levels of distortion and increased efficiency can be achieved when the driver voice coils are produced with thinner wire and precision winding processes. These manufacturing advancements means that low impedance headphones can reproduce music with improved detail, dynamics, and wider frequency range that the older designs could not achieve. The latest offerings of high-performance headphones require an amplifier that has been designed to harness the potential of these remarkable cans. The Violectric HPA V550 PRO is such an amplifier, and I have the good fortune of spending several weeks listening to my Focal Stellia headphones with this remarkable amplifier.

Violectric is a subsidiary of the Lake People electronic GmbH company. Located in the Southern German town of Konstanz, Lake People has an extensive history of providing products for the professional market. Lake People components are found in a wide array of venues from professional recording studios, broadcast companies, theatres, exhibition halls, and many other significant commercial sound venues. The Violectric components are developed in house by the Lake People engineering team, and the products are manufactured in Germany by internal production facilities, or in conjunction with carefully selected local contractors. Rarely do I include a link in an article; however, Lake People website has a headphone cookbook document that provides detailed information regarding the interaction between headphones and amplification circuits. I strongly believe this is a necessary read for anyone considering the purchase of top-of-the-line headphone equipment. Follow this link, you will find it time well spent: HERE.

In North America, the distributor for Violectric products is Power Holdings Inc. Arthur Power was kind enough to provide a review sample, and obtained additional information from the factory regarding technical questions I had about the circuit of the HP V550 PRO. From my experience, Power Holdings Inc. is an excellent distributor that will provide timely and in-depth support for Violectric owners in the North American market.

The Violectric HPA V550 PRO is a balanced amplifier, with each channel composed of an in phase and out of phase leg of amplification. Each amplifier contains 16 transistors in the amplification stage, and within the amplifier there are 50 transistors total with 32 of them assigned to managing the analog signal. This is not an amplifier based on chip sets, but rather a sophisticated design using primarily discrete components that the Lake People engineering team has endeavored to fine tune over the years. The first iteration of the Violectric circuit was introduced in 2009 and debuted in the V200 headphone amplifier. The HPA 550 PRO amplifier is based on that original circuit, and carefully evaluated and tested improvements have ushered it to the point where it stands today. The pre-amplifier stage of the HPA 550 PRO contains a user adjustable option named PRE-GAIN that allows for the user to adjust the strength of the input signal by a series of dip switches on the back on the amplifier. There are seven settings available, from -18/-12/-6/0/+6/+12/+18 dB. This allows the user to tailor the range of output available from the volume knob and maintain the lowest possible noise floor from the amplifier. The combination of precise volume control and low noise floor allows the listener to experience music at exactly the desired level and from the quietest of backgrounds. Finally, the HPA V550 PRO version uses a remarkable volume control. A 256 stepped volume control is designed around a collection of eight Reed relays. The contacts for these relays are contained in a gas filled protective tube, and a magnetic field initiates the contacts. The relays switch between 1% matched resistors and create a .4 dB step between each volume position. The result is superior cross talk and channel balance is achieved with this design.

The front plate of the HPA V550 PRO has inputs to plug in two sets of ¼" unbalanced headphone plugs, while there is one input for balanced headphones. The power switch activates a relay and provides a short delay as the amp stabilizes. A large volume control knob is on the left side of the unit, and the balance knob is located just to the right. The HPA V550 PRO is also a stand-alone preamplifier, which means there are RCA and XLR output connections on the back of it. Three closely grouped switches on the front panel control the signal output pathway, as well as a mute function, and an input selector. There are three sets of inputs available, two unbalanced RCA type and one balanced XLR input. A full function remote is provided, and it controls volume, mute, input selector, and activates the appropriate output stage. The chassis of the Violectric headphone amplifier is solid, nicely finished, and reflects a pride of craftsmanship. This component has an understated presentation that reflects the ideals of the Lake People, as the professional audio pedigree of this amplifier are easily recognized.

My listening sessions with the Violectric HPA V550 PRO amplifier were conducted with the Focal Stellia headphones. These cans are an ideal pairing with the HPA V550 PRO as they present a 35-ohm load and are 106 dB efficient. Since this is a dual-purpose component I chose to evaluate as a pre-amplifier and swapped it into my main system in place of a Halcro DM8 preamplifier. Digital source is an Audio Magic Kukama DAC being fed by an Intel Nuc i7 computer with Audirvana Audio music software. A TLP TF130 power conditioner provides clean AC power to the system. I spent 50 hours breaking the HPA V550 PRO in with music before embarking on any serious listening sessions.

High performance headphones are undoubtedly some of the most powerful "truth tellers" in the audio world. Slip on a pair of cans like the Focal Stellia, or any other topflight headphones, and you are rewarded with the most subtle tonal shades of instruments, delicate inflections of a vocalist's style, the reverberation of a recording venue, along with a myriad of other aural delicacies that are hidden within our chosen music.  There is a price to be paid when you use headphones of this caliber, as they do not tolerate the shortcomings of pedestrian electronics. I have paired the Focal Stellia with several mid-tier headphone amplifiers and I have experienced superb detail, however, on the edges of the music there has often been an aura of hardness, elevated upper frequencies, or an unnatural presentation of the music. There is a stereotype in the headphone world that Focal products have a reputation for being forward or analytical, although my experience of pairing the Stellia combined with the HPA V550 PRO is in direct opposition of this preconception. On the opening track "Soulville" by Ben Webster, I was captivated by the natural tone and texture of the saxophone passages, as I have never experienced the Stellia being able to have this intimate presentation and utterly beautiful texture. This album was recorded in 1957, and the piano passages have a unique sound that is defined by the recording and mic technology of this era, and the Violectric amplifier allows this sonic signature to come through without any significant alterations. The HPA VM550 PRO is honest and forthright with this recording, which what you expect from an amplifier of this caliber. The bass passages are powerful, exude wonderful tone, and reveal to the listener an enchanting waterfall of decaying notes that breathes life into the instrument as it captures your focus while the music cascades over you. The Violectric HPA VM550 PRO headphone amplifier and Focal Stellia phones provide a holistic experience for the listener, for they faithfully recreate all the emotion and passion our favorite musicians have worked tirelessly to bring to their audience.

From time to time, I will browse through various artists on Qobuz, and sometimes these adventures unearth some unusual music that I normally would not purchase. One such listening session brought me upon "Adeste Fideles" from the album Roman Catholic Hymns and Songs. Listening to the choir through the combination of Stellia headphones and the HPA V550 PRO amplifier was utterly mesmerizing. I could hear the space of the cathedral with the lovely reflection of the main chamber, and the power and majesty of this massive collection of vocalists. I could focus my attention and listen to specific groups of voices and move from one section of the choir to another, with a virtual panoramic soundstage set up in the confines of the headphones. No, this is not the soundstage created by a pair of loudspeakers, but in context of headphone listening this rendition of the soundstage fully envelopes the listener in a way few other headphones and amplifiers can equal. Without a doubt the Violectric HPA V550 PRO amplifier unlocks the full potential of the Focal Stellia headphones, and with program material such as "Adeste Fideles" I am fortunate enough to hear the beauty of this synergetic paring.

During my initial set up of this headphone amplifier I experimented with the PRE-GAIN settings, and initially selected a -12 dB position. I felt this setting provides me with the most precise control from the volume knob, although I also found the -6dB setting to be a solid candidate. I would have been satisfied with -6 dB if that was my only option. The PRE-GAIN settings allowed me to achieve the lowest noise floor possible from this amplifier, and I could always drive my headphones to the highest levels I would ever want to listen to. I certainly see the value of this feature, as I have owned other headphone amplifiers with limited control of volume when compared to the HPA V550 PRO. Another point worth mentioning is the relay and stepped attenuator combination is completely silent when changing volume settings. Many stepped attenuator assemblies will have residual noise from contact points disengaging and engaging, while the Violectric unit is free from this distraction. From an ergonomics standpoint every function of this headphone amp is superb, with switches, selectors, knobs, and input/output jacks exuding quality in every facet of its design and assembly.

Before my time with the HPA V550 PRO amplifier could come to an end, I felt it important to experience it as a preamplifier. One Saturday afternoon I disconnected the Halcro DM8 preamplifier from my system and re-routed the cabling to the HPA V550 PRO. The XLR jacks fed the main amplifiers, while the unbalanced outputs were assigned to the subwoofers. The unbalanced outputs have -6 dB signal strength when compared to the balanced outputs, although I was able to use the input controls on the subwoofer amplifiers to achieve a proper blend between the main speakers and subs. I believe the PRE-GAIN option allowed me to tailor the volume curve of the unit to facilitate a gain structure that allowed for a seamless blending of the AVM Audio amplifiers and Velodyne subwoofers input sensitivity. In the role of a dedicated preamplifier, I found the HPA V550 PRO to be a solid component, and there is an absence of fatal flaws that would limit this unit. I ended up listening to the Violectric headphone amplifier in that system all weekend, and I was content with its overall performance. I am not saying it is the equal of the Halcro DM8, however, even when paired with high quality gear the preamp stage in this unit never became a bottleneck to the system. When listening to "Blue Spanish Sky" by Chris Issak I experienced similar sonic traits as I did when using the HPA V550 PRO with the Focal headphones. There is a natural tonal balance to instruments, with an intimate and graceful presentation of the dynamic contrasts. The presentation of the spatial characteristics of the recording are somewhat diminished when compared to the Halcro, yet that is to be expected when comparing the preamplifier stage of this headphone amp against an upper tier two channel preamp. The Violectric headphone amplifier came out of this comparison in a favorable light, as it just acquitted itself against a component with a MSRP of $14,600 USD and did not get brushed aside. Essentially, the HPA VM550 PRO is an excellent headphone amplifier that also can be a respectable preamplifier if called upon to fill that role.

The lineage of the Violectric HPA VM550 PRO is borne from the world of commercial audio production. Lake People electronic GmbH is firmly established in that field, and has successfully branched out into the arena of personal audio with the Violectric brand. The HPA V550 PRO headphone amplifier is specifically designed to work with the latest crop of low impedance state of the art headphones, although it can be configured to pair with higher impedance models equally well. The balanced amplifier circuit is a variation of the 2009 design, although it is now compatible with lower impedance loads. The PRE-GAIN stage implemented in the Violectric headphone amplifiers ensures not only a low noise floor, but also precise control of output levels due to the ability to tailor the sensitivity of the pre-amplifier stage. The volume control is an impressive piece of engineering, as the ability to execute a 256-step volume control with .4 dB increments is nothing short of amazing. Finally, the HPA V550 PRO is a solidly designed preamplifier, and can function equally well in a traditional two channel audio system. If you are searching for a high-performance headphone amplifier then give the Violectric HPA VM550 PRO serious consideration, as there are very few products in the audio world that are built to this level of sophistication.

HPA V550 PRO Amplifier

Retail: $2799.95