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Reviewer: Ryan Clarin
Source: Meridian G07
Amp: Ray Samuels HR2, HeadAmp GS-1 [on rveiew]
Headphones: Grado RS-1, Joe Grado HP-2, Sennheiser HD600 w/Cardas, Sennheiser HD650 w/Equinox, Beyerdynamic DT880 [on review]
Cables: VH Audio Pulsar w/ Eichmann Gold bullets, Grover Huffman Ultimate Reference, VH Audio Flavor 1 power cord on Meridian G07, standard hospital grade power cord on HR2 and GS-1
Review Component Retail: $749

The GS-1 HeadAmp is a relatively new offering built by Justin Wilson over at HeadAmp Audio Electronics. It's a solid-state headphone amplifier priced at $749 that offers a versatile option in the realm of headphone amp choices. It incorporates two inputs, two outputs (preamp and tape), two headphone jacks and the ability to switch between lo and hi-gain modes (9 and 18dB). The amplifier is designed to accept various custom amplifier modules to remain plug'n'play upgradeable should much improved sonics by way of new modules become available in the future. The standard module shipped with the present GS-1 is based on a purely discrete circuit designed by Dr. Kevin Gilmore.
According to Dr. Gilmore, his fully discrete Class A circuit is "a dual differential input amplifier in a balanced configuration made of matched ultra low noise JFET transistors, and driven by a pair of matched current sources which are controlled by a completely unique servo amplifier for the ultimate in DC stability. The circuit also features a high bias pure class A voltage amplifier stage with a 3-resistor Class A bias for the final current amplifier stage. The current amplifier uses many smaller devices in parallel for the ultimate in speed and a minimum of distortion. Overall loop gain is kept to an absolute minimum to ensure flat frequency response and minimal intermodulation distortion."


Mr. Wilson adds that "discrete circuitry is becoming a lost art in audio design today as more and more high-end manufacturers opt for chip-based designs which may reduce development and assembly expenses but at a cost to innovation and performance. You can still find circuits of similar philosophy to Dr. Gilmore's in some of the most high-end equipment available, i.e. pre and power amps costing thousands of dollars or more. In the GS-1 and some of our other products, we've implemented such a design at a fraction of what these high-end pieces sell for. This is one thing that makes HeadAmp unique in a headphone amplifier world that mostly consists of op-amp based products."

The headphone amp is a one-box design, with the power supply, input and output stage all in one chassis. Mr. Wilson, when asked about the power supply, commented that "it is a simple but effective linear regulated design. It uses a quiet toroidal transformer. The rectification stage utilizes high-end Schottky diodes. The positive and negative voltage regulators are each bypassed several times with electrolytic, tantalum and ceramic capacitors for stability and filtering out noise at all frequencies. A lot of effort has been applied to ensure the power supply is as quiet as possible through other means as well, such as positioning of components and routing of ground traces and planes. Designing and implementing a high-performance circuit with success is as much an art as it is a science. We use massive separate ground planes to prevent any leakage of noise or hum from the power supply coming into the signal path."
Off the bat, the GS-1 conveyed dynamic range that encompasses the smallest of pianissimos to the tallest of fortissimos with plenty of weight and impact across the board. On Ravel's Bolero, the beginning section's dynamic level of the piano were clearly articulated and as the dynamic forces increased, becoming louder and more intense towards the finale, the GS-1 clearly tracked each new level of dynamics, each one being focused, precise and with plenty of control behind it.
On Mogwai's "Dream Team" [Young Team, Chemikal Underground 018], the band suddenly goes from a low piano to a wailing forte on two separate occasions. The effect is startling and heart-pounding, with the GS-1 handling the dynamic scaling with
utmost control, allowing the music to jump out of its shell. This listener could really feel the weight and impact of the music specifically in the bass region. The GS-1's bass output is tight and tuneful but has plenty of body and impact to really hit you in the chest depending on the recording.
On Bela Fleck's "The Sinister Minister," [Greatest Hits of the 20th Century, Warner Bros. 47301], Victor Wooten's bass line is powerful and dynamic with plenty of heft but no bloat. The bass on the GS-1 is like a tough, well-toned middle-weight boxer - light on the feet and
fast but with plenty of power to knock anyone out, at the same time not overly brutish or unnaturally built up to detract from speed of delivery and athletic agility. On "Flight of the Cosmic Hippo", you can really hear why the track is named as it is. Wooten's bass line takes on a whole different character, showing the ability of the GS-1 to reveal whatever the recording and gear upstream is capable of doing. Here the bass is drawn out and the character of the
song is in perfect sync with the bass line. Drums and percussion have great impact as well, with plenty of snap and pop. Max output voltage is 7VRMS.
On Brubeck's "Take Five" [Dave Brubeck Quartet, Time Out, Columbia/Legacy 65122], you should be able to picture how far the drum stick is above each snare and cymbal crash and see the force behind it. The GS-1 is top-notch in this area, showing itself as a very dynamic amp, with enough power and reserves to drive the music straight into your chest during its loudest peaks, but also with the finesse and refinement at subdued interludes to keep all the natural percussive forces perfectly intact.

The GS-1 has great presence and vitality. On Bela Fleck's live track "Stomping Grounds", attacks are clean and fast, with transients neither hyped nor blunted, clearly conveying the live

aspect here. The banjo's consistent 16th note lines are perfectly articulated to provide a lively pace and great rhythmic groove, with the band playing well within the pocket.
On Duke Ellington's Money Jungle [Duke Ellington with Charles Mingus and Max Roach, Blue Note 38227], "Caravan" is one tough piece whose abstract rhythms and melodic breaks can leave a listener confused if she doesn't know what the piece is about. The GS-1 acquitted itself well, with ride cymbal and bass cleanly separated. I next played Pink Floyd's "Money" from Dark Side of the Moon [Mobile Fidelity UDCD-517] to see how the GS-1 grasped its asymmetrical meter in 7. It rocked, plain and simple. The bass quarter notes were spot on, the guitars placed with pinpoint precision, and all the stereo effects added to the momentum rather than detract from it.

I played through all of the Buena Vista Social Club [Elektra/Asylum 79478] and was startled by how I could listen and focus on a single instrument or sit back and just absorb the group as whole, basking in its rhythmic cohesion. The GS-1's strengths do not end with timing, however. The amp casts a nicely layered soundstage and the ambiance of the venue is allowed to ring and resonate. On Robert Shaw's interpretation of Rachmaninoff's "Vespers", each vocal part is located precisely along the Y-axis of the stage, with great height from top to bottom and a clear recreation of the venue. The depth of the stage is surrounded by blackness but there appears to be a wall that constricts within the occipital.
During the lower tenor sections, I should hear them emanating slightly behind the neck area, an illusion somewhat lost on the GS-1 while voices far out in front of me were captured nicely. To get a better sense of imaging precision, I cued up the fourth track of Chet Baker's Live in Tokyo [Evidence 22158]. The GS-1 maintained great separation and clarity. Imagine a wide and deep stage, each performer outside of the head to each side and way out in front and even below your chin area while the performance ties together
completely as one entity. Spatial and reverberant cues are fully resolved especially during the softer sections. The GS-1 l provides a huge stage only lacking some depth behind the occipital.
I have stated before that in order to have great low level resolution, an amp needs to have as black of a background as possible. The GS-1 not only has blackground, it takes it a step further. A black background still implies a canvas of some sort. With the GS-1, the canvas vanishes and sounds appear to emanate out of pure space and air. In conversations with Justin Wilson, he confirmed that this was one of his major areas of focus. The decay of notes is startling. You can hear each reverberation as it lingers slowly into oblivion. The GS-1 also has a great sense of air especially in the treble region. It sounds delicate, sweet and incredibly smooth, without any hash or grain.
On Broken Social Scene's "Pitter Patter Goes my Heart" [You Forgot it in People, Paper Bag 001], the strings swell and decay beautifully and their upper harmonics are unrestricted. Other than sheer bass output and control, the highs are my favorite part about the GS-1. It is free of extraneous sibilance and extension appears well beyond the capabilities of human hearing. As a vocal teacher and choral director, I stress to my students the need to achieve a sense of openness to their sound, to allow their high notes to sound full and unrestricted. The GS-1 captures this sensation of openness
in its treble region incredibly well. They say music is just as much about the rests and silences as it is about the actual notes. I played some Kurt Elling scat sections [Man in the Air, Blue Note 80834] to see how well the GS-1 captured the space between each of his notes and syllables. In a word, flawless.
Every review falls under an umbrella of system synergy and listening preferences. My biggest qualm with the GS-1 was how it's voiced in the midrange (0.006% THD). Instrumental timbres here are not as warm as I would personally like them to be. The GS-1 seems to lack warmth in the lower mid and upper bass range. However, the sound isn't cold or sterile. The GS-1 has a smooth and even tonal balance. If anything, the GS-1 is closer to that ideal of dead-on neutrality than my Ray Samuels Emmeline HR-2, which is a bit warmer in the power region. At times, I felt the mids of the GS-1 could be just a bit more pronounced especially compared to the liveliness of its highs and its boxer-like bass output. Chalk it up to personal listening preference - I prefer a more liquid, organic midrange.
I had a Jolida JD-100 CD player whose tubed output had such a glorious midrange that I almost forgot about some of its grainy highs and bloated bass. I then discovered the Meridian G07, which fixed the treble and bass issues, maintained the sweetness of the midrange while adding
much more refinement in soundstaging, resolving power and timbral accuracy. And I love what could be called the Grado midrange magic. The GS-1 does nothing fancy with midrange tricks and I feel it is simply being faithful. The GS-1 doesn't play any games with your music. The only barrier I personally had was the aforementioned lack of warmth in the lower mid and upper bass region, and a midrange that sounded perhaps slightly recessed at times. My copper Pulsar cables helped a lot in creating the kind of sound I fancy. The Grover UR is very neutral and transparent and coupled with the GS-1, too much of a good thing. The Pulsars brought a nice warmth to the midrange and the lower mids and upper bass blossomed a bit.


At $749, the GS-1 offers tremendous value and versatility and follows a design philosophy of straight wire with gain with no additive or subtractive qualities. Dynamics, timing and a superior noisefloor (better than 100dB) are this amp's greatest strengths. As a result of the latter, ambient cues and micro details are fully resolved and the treble is wide open yet subtly on the warm side.


With the GS-1 in my system, I realized I could easily live with this solid-state amp for a long time. For synergy, I would mate it with cables that provide added warmth to the lower mid/upper bass transition. The GS-1 sounded great with all the headphones I had on hand. My Grados lost a bit of their midrange magic but their upper-mid peak was balanced out nicely. The Sennheisers cottoned to the clarity, separating acuity and depth of stage of the GS-1 and made a very synergistic combination. This HeadAmp creation offers crystalline elegance in the highs, superior bass output, wonderful separation and detail and can drive a wide range of headphone impedances. It's a smooth non-fatiguing performer and high-value flexible proposition that can operate as a wonderful bridge between your high-end source and headphones.
Manufacturer's website