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Positive Feedback ISSUE 5
headroom the Max and Little headphone amplifiers
as reviewed by Carlo Flores
Many audiophiles view headphone listening as playing with toys or trying to get the most from portable fidelity. Others believe that a well-designed transducer powered by quality amplification can yield good results regardless of the type of system. Headphones offer a choice to those who are limited in space. If you can live with a soundstage that exists within two inches of your skull, you can, with proper care, assemble a system that rivals similarly priced speakers. There are headphones and amps to power them in just about every price bracket. In the case of Headroom, a complete line of headphone products is available from one manufacturer, including the Blockhead, a fully balanced amp that can only be used with a specially terminated Grado RS-1 or Sennheiser. For those (like me) who like other headphones, the Max is Headroom's best offering, so I view it as their statement product, and the one I decided to review.
The Max has some nice features that allow for great flexibility. It can be used as a two-input active preamp, a one-box solution for those looking to incorporate a headphone amp with a speaker system. One of its inputs can be changed to a loop out, so the user can use the amp between a preamp/integrated's tape output and a recording device, with minimal influence on the sound. The Max's class AB circuitry is encased in a long rectangular chassis that is about half the width of most stereo components, with the simple, nondescript faceplate allowing for easy integration into a living environment. The Max's front panel is covered with user controls: toggle switches control gain (a welcome addition for better control of the stepped attenuator), Headroom's patented Crossfeed Circuit, and their filter settings. Two headphone jacks that lock in theory, but not in reality, allow for shared listening, and a toggle switch allows the user to float ground. Missing from the front panel is source selection; instead, it's on the rear plate, which will make the Max unpractical for many people. On the back, the IEC receptacle, fuse, and power switch are a one-piece unit, which means that that the large IECs on some power cords may get in the way when trying to turn the unit on or off. The Max is surprisingly lightweightI had to place books on its top lid to use aftermarket power cords.
After the obligatory interconnect and power cord changes, I settled on the Tara Labs Air 3 for its soundstage and the Tek-Line PC12W for its top end linearity. I set the Max's crossfeed circuit and filters to their off positions (more on what they do later), and hardly fiddled with the amp again. I had the opportunity to borrow Grado HP-1s, Audio Technica w2002s, and Sennheiser HD600s during my time with the Max, along with the Grado SR225s and Sennheiser HD580s (with Cardas upgrade cables) that are my current headphones, so I got to experiment with many headphones to define the amp's character. As always, all of my sources were connected directly into the amp.
The Max is full-bodied, with decent tone, an accomplishment for an op-amp-based headphone amp. Give the Max bass guitars and it can carry the tune. Entwhistle strums God-like through it. Notes are well defined and clear, with enough body and impact to ignore most of the low-frequency limitations of headphones. Kick drums sound more like nudge drums, but the Max still does them better than any commercial headphone amp I've tried. The amp's control of the lower notes jumps out at first listen, and still surprises weeks later. Attack is there, body is not exaggerated, and decay is natural, with speed, slam, and all between. The foundation of the Max's sound is its bass, and everything builds up from that.
The amp also has a rich tone with lead and rhythm guitars, giving enough space for acoustics and enough edge for electrics, all without glaring or offensive flaws. There isn't much to fault when it comes to the midrange. Ask it to show speed with Tricky's Maxinquaye and Portishead's Dummy, and it does admirably. Throw on the Stones and listen for dynamics and theyre there. Try Joni Mitchell's Blue (DCC's master) for soundstage and it creates a space that is neither big nor small, just well placed. Move upward in frequency, however, and that relaxed presentation turns soft and diffused. The Max doesn't extend to the heavens, and its diffused sound with cymbals is as noticeable as its fantastic response with bass. You'll get the shimmer, but don't expect the first strike to have any real authority.
The Max sounds, in many ways, like the Sennheiser headphones that Headroom considers their reference. Pairing the two highlights the strengths of both without any attempt to correct the HD580s and HD600s' sonic flaws, instead providing plenty of power for them to perform well. The Max is a fantastic mate for the Grado SR225s, keeping those headphones (which have a tendency to get sloppy at both frequency extremes) under control at low and high volumes. The Audio Technica headphones sounded bland and uninvolving with the Max, but the Grado HP-1s just got out the way. The Max didn't accentuate anything with the HP-1s, and didn't mask much either. After several listens, the HP-1s (along with, at times, the Sennheiser HD580s) became the only headphones I used with the Max. Throughout the headphone changes, the gain selector was used quite a bit, allowing for the desired volume regardless of the load or the limitations of the stepped attenuator.
I frequently use certain albums when judging an amps character, and one of those albums is PJ Harvey's Stories from the City, Stories from the Sea. Those driving guitars and wicked bass were in full force here, with transients and dynamics behind so much speed and impact that it was easy to find my foot tapping. The Max just lets the notes go, with both the Grado and Sennheisers adept enough to let that through. This isn't the best-recorded album out there. While a champion at driving dynamics, it has some hardness in the upper frequencies and Harvey's voice gets fatiguing through ruthless equipment. With the Max, its polite, listenable, and enjoyable. The leading lines of pianos and other keyboards are excellentwell placed, defined, rawwhile giving the separation that is usually only found in discrete designs (the Max is based around the OPA627 op amp). The dubbed voices come in from left to right to in-between, each in its own space but without the haunting qualities of, say, the E.A.R. HP4 or the Sugden Headmaster.
I suspect that Headroom took very good care of the power supply when designing the Max. Its backgrounds are so black that transients and detail pop out, rich and colorful, and its an engaging listen. As I said earlier, the sound never feels strained when making a dynamic swing, always hinting that it can take whatever the recording has to give. Texture and scale need to be correct for me to be satisfied, and the Max holds its own proudly in this regard. On Radiohead's Kid A, the sweeping, polyrhythmic beats create a base for everything else, with synthetics and Yorke's voice sweeping above them. Once again, this amp builds the sound from the ground up, starting with tight, strong, impactful bass lines and letting the rest fall into place. There's no lost speed"Idoteque" and "Everything In Its Right Place" have pace and timing that hint at the order behind the obvious chaos. The speed with which the Max sets it all up hints at second-order harmonics and tubes. Calling a solid state amp tube-like is code for "It sounds good but might not be the most ruthless out there," and in that sense the Max is tube-like. Kid A has information on top of information on top of more information, and with the Headroom amp, some is lost. Greenwood's madness falls into the depth of the blackness and turns diffused when trying to screech high. Pleasing, yes, but an open window to the source it isn't.
The Max's minor flaws are only apparent on some recordings. On Lucinda William's Car Wheels on a Gravel Road, the guitars sound fresh and her voice distinctly her own. (On lesser headphone amps she sounds like a Sheryl Crow imitation.) Drums, including cymbals, are centered, and her voice floats right in front of them, with bass guitar in an intermediate space. The Max has a habit of centering instruments instead of spreading them out, but that only becomes apparent when comparing it to great and much more expensive designs incorporating tubes (the Cary SLI-80, the E.A.R. HP4, a Modified Melos Maestro), and even then the Max's linearity in the bass lines and its transient response with percussion is enough for it to hold some ground against products way beyond its price bracket. Talkin' Verve: Wes Montgomery never sounded congested or stuffy, just clear, open, and laid out. My early vinyl pressing of Jimmy Smith's Root Down had me sinking in my chair, lost in the music.
Headroom's Crossfeed circuit attempts, by slightly delaying left channel information and feeding it into the right (and vice versa), to simulate the dispersion pattern of speakers. To offset some of the high-end rolloff experienced by some users, filter settings (bright, brighter, or off) are provided. I'm a purist at heart, and find the idea of the crossfeed circuit to be slightly annoying. Headphones have their own strengths, and simulating speakers isn't one of them. The effect is like bad upsamplingmore body and a fuller sound at the expense of linearity. While it's subtle on some recordings, it sounded more like a "tube effects" switch than anything else, and I didn't like it. The amp's strengths are lost with it, and I don't think it should be used for anything except listening to very bad recordings.
As a preamp, the Max is capable but not extraordinary. It provides enough gain to control the Conrad Johnson Sonographe, and thus to power most speakers. The sound is still full and lush and the bass lines nice and extended, but it lacks the sharpness and leading lines that are offered by my modified Anthem Pre1L. Just as the Pre1L is a better preamp than it is a headphone amp, the Max is a better headphone amp than it is a preamp. It also can be used in the tape loop of a preamp or integrated without taking up too much space.
So, yay or nay? The Max didn't give me the combination of transparency and linearity that I look for from a headphone amp, but I've found that I can't achieve that from a commercial product. Many would consider the Max to have the best combination of strengths. It is certainly worth an audition, and worthy of building an excellent headphone system around. It is better as a preamp than all but the most expensive headphone amps. It never fatigues or annoys, and gets the foot tapping. It's a great product from a company that makes customer support a priority, and its dynamics, black backgrounds, and sense of ease earned my recommendation.
On the other end of Headroom's product line is the Little, an op-amp-based headphone amplifier aimed at those looking for an entry into this aspect of hi-fi. The Little can be modified by the manufacturer with a hard-wired, regulated power supply and Headroom's Reference Module for the signal path. Headroom claims that the Little, when upgraded, can compete with many other headphone amps.
As the name implies, the Little is extremely small, and it is just plain cute. The main front panel is about the diameter of a common jar lid, its feet so close together that it could easily sit on one. The separate power supply has a long cord, and it can be placed out of the way. Selection of Headroom's Crossfeed Circuit is on the front panel. There is no power switch, but this thing isn't going to dent the electrical bill. Headroom's manual is clearly laid out, and makes the Little very easy to use.
I first used the amp with my normal sources, and found much to be desired. When driving Sennheisers, the amp sounded strained, with too-harsh leading lines and a leanness across the spectrum. With Grado SR225s, it was just plain hard, with a lack of tone. It was too easy to hear the generic op amp and know that the Little isn't class-A biased. The softness and warmth brought about by Headroom's Crossfeed circuit provided relief, making the Little much more listenable, but it was still no champion. Bass lines had a one-note quality, voices lacked presence, horns were hard and grating, and there was too much not to like. Im sure that Headroom's upgrades improve it, but the basic Little couldn't hold its own in my main system. But we are comparing what I consider my "best" with an entry level component here. Not really a fair comparison
I then moved the Little to my cluttered desktop computer station, clearing out a small spot for it and putting its power supply behind the CPU. I never picked up any RFI from the amp, and found it useful for this application. My computer has not been made into the high-end source that it could be; instead it uses an inexpensive generic sound card, a somewhat decent transport, and shielded cables. Ive also replaced the fan to deal with noise problems. The Little, with the Crossfeed circuit driving Sennheisers, did well. Bass lines still had the same one-note quality, but with deceptive separation, though when compared with other headphone amps, it was lacking in texture and definition. Crossfeed tamed the top end so that listener fatigue didnt set in, and I found myself happily listening. High end it isn't, but for those with a small amount of space and with a compromised source, the Little is extremely convenient and provides just enough sonics to get by.
The Little will sound better than most headphone jacks and soundcards. It has enough power to give many headphones some bass response and hint at dynamics. It would be a great gift for a dorm resident or for those looking to add headphone listening to their work environment, but who don't have the space for a mid-sized amp. Never the less it sounds exactly like what it isa relatively inexpensive amp in a small (and pretty cool) chassis. Its fit and finish is better than others at the price, and its upgrade path will allow you to improve it at your own pace, but don't expect the sound of the Little to blow your mind like the Max or other higher priced headphone amplifiers.