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Positive Feedback ISSUE 30
march/april 2007


The Newest from HeadRoom: the Desktop Balanced Amplifier

as reviewed by Max Dudious



New developments always seem to sneak up on me, on tiptoes, and then I'm left slapping my forehead with the palm of my hand (the sound of one hand clapping: smacka, smackus, smuck), saying, "Gee, I didn't hear that coming." I always feel like the prize patsy at the poker game who doesn't catch-on that he's been "it" until he catches the other guys' furtive glances as they're counting their winnings. Oh well, that's me. You too? Sorry. It was obvious that someone, somewhere would come up with a headphones amp that employs these particular new developments, leaving me with the only option of one-handed applause. Leave it to Tyll Hertsens and the gang at HeadRoom to earn two-handed applause. Kudos on this one, guys and gals. You certainly nailed it this time.

If my steel trap (hah!) memory serves, my mentor Jonathan Scull had a pair of Lynn 500s with switched-mode power supplies some years back when I visited him and his fair Kathleen in their fabulous listening room. The Lynns sounded right decent, just shy of etherial on his system. He explained to me that switching supplies were the wave of the future, and they would become better accepted once the engineers got the last little bugs out. (He's a great explainer.) During the calendar year 2006, the price of copper and iron used in transformers mysteriously went up suddenly, and this forced engineers the world-over to start taking switching supplies more seriously.

This review is about three or four wrinkles that have a synergistic effect on each other, that just happen to pop up in this one new piece of gear, HeadRoom's Balanced Desktop Amp. They are: a punchy new switching-mode power supply; a built-in, sweet-sounding digital-to-analog converter (DAC); a Class-A-biased amplifier section; and an optional balanced-line configuration from back to front. None of these is so original that it is patentable in itself, but together they seem like a breath of fresh air on my tympanum. The result, at first hearing, is seeing farther into headphone sound (to mix metaphors once again) than I've experienced before. That is to say, the sound is a notch or two more punchy yet more liquid, cleaner and more spacious than what I've grown used to, mining more gold (musical detail, texture, clarity) from the raw ore (data stream), which is pretty fine, and amplifying it meticulously into 24 karat sound, which is damn fine.

Switching-Mode Power Supplies:

Power supplies used to be pretty easy for me to understand. Once upon a time (before torus-shaped transformers), there was a transformer that was a series of copper windings on a cross-grained metal jig, usually shaped like the letter E, that "transformed" house current to the proper voltage and was designed for whatever the circuit called for (via primary, plus secondary, tertiary, even quaternary windings). This was followed in a block diagram by a large filter cap. Sometimes there was also a choke, or wound-copper inductor to roll off ultra high frequency signals; then a diode bridge, or a rectifier tube, that converted the current from A.C. to D.C.; then one or more large filter capacitors that smoothed out the ripple (small amounts of A.C. found "riding" on the D.C.) from the current. In many pieces of solid-state gear (with no output transformers), such a traditional power supply might account for well more than half their weight.

Power supplies attracted a lot of attention in the upper reaches of the audio hierarchy because all the current that goes into the active amplification circuits first passes through the supply. The power supply is where the rubber (house current) meets the road (the needs of the circuit). Designs varied, but there seemed to be many that involved more parts rather than less {the pi filter input configuration (transformer, filter cap, choke); and push-pull pairs of rectifier tubes – for two examples}. Some old tubed amplifiers, such as the Fisher 50-A, used both these elements.

Some ideas in play were: make the power supply as "stiff" as possible, so it would not "sag" when delivering sudden peaks of current. (Aren't engineers naughty with their terminology?) This became more important in stereo playback, where often there were sudden peaks on the left channel, then on the right, and the soloist would seem to leave the center and ping-pong back and forth from left to right—depending on what the rest of the orchestra was doing. Or, the sound-stage at low level would seem to be large, but grow smaller in width and depth as the gain increased. These anomalies caused the design engineers to spend more time designing stereo-appropriate power supplies.

Soon, by a series of experiments (and some dumb luck), it became clear that the current supply ought to appear to the rest of the circuit (as near as possible) as an infinite source. This would "fool" the circuit into "seeing" an ocean of microfarads in reserve. Even if the circuits only drew, say, 150 milli-amperes (0.15 of one amp) at most, it proved best to build a 5 amp or even a 10 amp power supply (as if for a 22 cu. ft. refrigerator/freezer). And this for a pre-amp, not a power amp. The power supply had to be able to handle the complex demands of stereo music, from a cymbal's overtones to a barrage of live cannon explosions, from soft to loud, all the while maintaining the subjective experience of a large sound-field.

Today, with hi-resolution CDs delivering up to 120dBs of gain (as compared to LPs with up to 60dBs, and don't forget the dB is itself a logarithmic measure) the emphasis is on being able to go accurately from very, very soft to VERY LOUD. Kara Chaffee, chief design-engineer at de Havilland Audio, believes "the ear takes its loudness cues by the dynamic contrasts available... The dynamic scale has to be intact." I think, in terms of this conversation, she is highlighting that reproduced sound will be a convincing facsimile of live sound to the extent that it accurately mimics performance with regard to increases and decreases in loudness (taking freedom from peaks and dips in frequency response as given). To deliver this, a stable, brawny power supply is indispensable. Kara has created one de Havilland design with which I'm familiar (the Ios I reviewed last summer), that uses five separate custom-designed transformers. At the high end, bigger and better power supplies have become, like "jacks or better" in poker, a minimum requirement.


Before long, as the power supply weight went up, the mid-fi Pacific-rim manufacturers started using "switching supplies" to cut the weight of individual pieces of gear. To quote Wikipedia:

A switched-mode power supply ...or SMPS, is an electronic power supply unit that incorporates a switching regulator—an internal control circuit that switches power transistors (such as MOSFETs) rapidly on and off in order to stabilize the output of voltage or current. Switching regulators are used as replacements for the linear regulators when higher efficiency, smaller size, or lighter weight are required.

I first noticed them on entry-level receivers. I'm not sure exactly which manufacturer was first, or the release date of the first switching supply, but six pound stereo receivers (tuner/pre-amp/amp) seem to have been around for about 25 years, now. Imagine you head a firm that manufactures many, many pieces of gear annually, and you can suddenly reduce your shipping costs by more than half. You can see how today, with increased costs of copper windings, any well-trained M.B.A. worth his profit center would want to cut that shipping cost.

In the beginning these new switching supplies were known for being complex (relative to the simpler old transformer/rectifier/capacitor type), expensive (lots more parts), and noisy (suffering from hashy, not silent, backgrounds due to high frequency noise and "birdies"). As time rolled along, newly developed parts and suppression schemes became available, the SMPS needs were more easily met, and the price came down. With better filtering, and lower costs, the SMPS can now compete with the standard pre-amp power supplies on even terms. Now they have to become "all 'round" competitive, beyond the pre-amps' (or phones amps') low current needs for which they are particularly well-suited. The Lynn 500's show it can be done for power amps, as well.

For example, my HeadRoom Desktop Millett Hybrid amp came with a wall-wart type power supply that takes AC house current and transforms it to 15v. DC (+ & -) with a capability of delivering 240 milli-amps (.24 of one ampere). By contrast the new brick-shaped SMPS "Brick," which is standard with the Balanced Desktop and which is perhaps a notch more quiet (by listening test, or ear-balling), can deliver 1.35 amperes. That's an improvement of over five times as much available current, and that begins to look like, if not a sea of energy, at least a great lake to call upon as needed. Audibly, I can say with assurance, the higher-rated brick-shaped SMPS delivers bass drums shots more loudly, exhibits considerably less strain with the extreme highs and lows, and sounds cleaner over-all than the earlier "wall-wart" through my Millett Hybrid, through the Balanced Desktop, and through all the headphones sets I've auditioned with it (alphabetically: the AKG 701, the Grado RS-1, the Grado GS-1000, and the Sennheiser 600).

Things got foggier when I compared the "Brick" to the older, more fully regulated Desktop Power Supply (DPS). The 600 milli-amp rated DPS was designed to power up to six Desktop components (say, a stand alone DAC, a CD player, a Desktop amp, etc.), but is here used only to power the Millett or the Balanced Desktop amps. The DPS supply is a conventional transformer type design, very well executed, very quiet, with a large reservoir of supply capacitance. (It takes about a minute for the green on/off light to go down.) It is a tad less punchy than the 1350 milli-amp rated "Brick", but the DPS is a bit quieter and a bit better controlled, and with the Millett's tubed output stage reproducing female vocalists, the midrange became angelical, drop-dead gorgeous.

I recognize how the two power supplies could be taken as a matter of taste, or preference. I'd guess those who like a more refined presentation would like the traditional $400 DPS supply, and those who prefer a more dynamic presentation would like the $100 "Brick." And with the front-end all tricked out with digital feed, using the internal DAC, the balanced-drive feature, and the balanced line headphone cables, it becomes increasingly harder to make a case for either one over the other. The power supplies began to sound so similar, the differences so small, it was hard to choose. Aye laddies, "The divil is in the d'tails."

I feel "The Brick" is a reasonable expense to improve any HeadRoom amplifier currently using a wall-wart that will also accept the Desktop Power-Supply. "The Brick" comes with the standard Desktop Balanced Amp, and is included in its basic price. "The Brick" seems cleaner, and it definitely has more punching power than the wall wart that came with Millett's amp—when I compare the wall wart and the "Brick" through my tubed (and still great sounding) Desktop Millett Hybrid Amp.

For a more detailed explanation of how switching supplies work, go to:

Built-in DAC

Every portable CD player that goes jogging every morning has a built-in DAC that converts the bit-stream from digital pulses to continuous analog. This can be done with a small surface-mount chip nowadays, and a smaller cluster of auxiliary surface-mount parts, which makes a compact fit for a walk-around CD player or pod. The DAC inside the Balanced Desktop is special, designed to do its job very well, and to match the "sound" of the rest of the amp. That is to say, the converter itself is made of very carefully chosen parts, and at its heart beats the Cirrus Logic's flagship chip, its 24bit/192kHz, 120 dB Digital to Analog Converter. It is isolated and tightly regulated. In the analog section of the DAC are found two high quality Burr-Brown 134, single package Op-Amps, with only discrete metal thin-film resistors and poly-phenylenesulfide (poly-film) capacitors nearby.

Such parts selection provides continuity of design with the output stage of the amp, so there is no audible discontinuity to the sound. Everything is meant to match. This may or may not be true of the inexpensive walk-around CD players, that might get their DAC chipset (and auxiliary surface-mount parts) from one manufacturer, and their audio op-amps (and auxiliary surface-mount parts) from another. The Balanced Desktop sounds as good as it does (which is super) because of discrete, high quality parts matching in the design stage of production. So when the analog audio signal comes to your headphones it's as well matched and balanced as the HeadRoom gang can. That means squeaky clean and punchy, yet liquid and silky sounding. However, the built-in DAC at the Home level is designated as an upgrade.

Again, for more information on DACs, go to:

Home Module Upgrade

As has become their practice, HeadRoom offers upgrades at each price niche of the Desktop line. The next stage of tune (in car talk) is the "Home Module Upgrade," which amounts to still higher grade and more discrete parts in the circuits. Here, I'll quote theowner's manual: "The Home Module consists of two pair of 4-layer circuit boards (one each for the left and right channel) that are connected with a series of header pins used to solder the module to the main circuit board. This module is designed to sound great without going up the ridiculously steep part of the diminishing returns curve. The output current amplifier is our version of the highly regarded Diamond Buffer discrete transistor design by Walt Jung {He's an old audio buddy of mine. See The Pooge Chronicles, (The Audio Amateur Press, 1997) for an article we wrote in 1981.}; internal input buffer, crossfeed, summer, and gain stage use the Burr-Brown OPA2134 op-amp. All these active circuits are forced into class "A" bias with constant current sources. Resistors are 1% metal thin-film, and caps in the signal chain are poly-phenylenesulfide (poly film). The sound of this module is not only well balanced and punchy, it's also liquid and integrated. This is a sweet listen."

Stepped Attenuator Upgrade

Standard HeadRoom amps come with a damn good Alps pot. But due to industrial process, though it sounds and tracks very well, there are spots at some settings where there just has to be a little unevenness between the loudness of the channels, and (over time) a little layer of particulate matter accumulates on the wipers due to numerous passes over the plastic conductive element. Such imperfections are eliminated by using a stepped attenuator instead, which is "simply a multi-pole switch that allows you to select one of a series of resistors to adjust the volume."

The 'Quad' Stepped Attenuator, for Balanced Max and Home AmpsThe way the designers at HeadRoom have chosen this part and how they use it makes it a cinch to sound better, and sound better longer, than a standard pot. I agree, based on experience with some stepped attenuator volume controls I built twenty-seven years ago that are still in splendid use. In general the additional expense of a stepped attenuator seems unwarranted at first, but they will outperform all comers over time. They sound neutral, track famously well (hell, you don't see a balance control on either 'phones amp), and are long-lived without starting to sound like the crackling cellophane package wrapper the jerk next to you at the movies insists on opening during a quiet part. Making this upgrade available is great. I'd advise anyone to get a stepped attenuator if he expects to have his headphone amp in heavy use over a long time, like me.

The Home DAC Upgrade

This DAC upgrade is similar to the Home Module Upgrade in parts improvements, the use of discrete part, op-amps biased up to Class A, and the use of three low-noise, ultra-low-dropout power-supply regulators that isolate and regulate the various digital, analog, and mixed signal circuits. As Tyll say, "The result is the kind of liquid clarity found in multi-thousand dollar high-end CD players."

I can attest to the HeadRoom copywriter's enthusiasm for this Balanced Desktop Amp. It is really something, and it makes my Sennheiser 600 sing like a gifted soprano, with the Grado RS-1 singing contralto close-by. This little amp makes you want to hear old favorites again and again because it captures micro-details that few similar amps manage to bring to the surface. It captures the small details of performance that develop a connection between the performer and the listener. It puts me in touch with the genius of my favorite composers and performers, past and present, and that gives me a greater emotional bond with their music.

One of my audio pals (Robin Landseadel) tells me I might be an audio Shaman without even knowing it, trying to recall the spirits of genius past with my magical audio rites and conundrums. Who was it that once said, "Love Genius! It is the face of God." English mystic-poet-painter William Blake? Whether that is literally true or merely more of Blake's poetry, I find it reason enough to pursue a connection with Beethoven, say, whose marble bust sits atop one of my Hartley/Klipsch horns. You might see me some night, switching on my amplification in just the right order so as not to swamp my speakers with booms and pops, mink-brushing the dust from my Grado cartridge's stylus, buffing my LPs and/or treating my CDs with Brillianize, making sure my Souther linear tracking tone arm is properly tangential and perpendicular, checking to see if my magic chair is equidistant from my Lowther speakers, sipping exactly one two ounce portion of my favorite inexpensive, single-malt Scotch, (Speyburn), etc. etc.

"Aye, what's that? You'll nay drink wi' Max? Fie on ye."

Balanced Line Ground Scheme

Theoretically, a balanced line ground scheme ought to be noticeably cleaner, with inky black silences, and fewer mystery signals that originate in some radio frequency (out of band) anomaly or micro-wave transmission that sneaks in between the stator and rotor of your LP turntable's or CD player's motor, rides its ground back to a common ground in the currently well-thought-of "star ground" configuration, or further back into your system, or house, to a ground buss in a fuse box, and through that route enters your audio feed. The balanced line ground scheme theoretically eliminates the possibility of this chassis ground's contaminating the "return" signal. So the analog input to the Desktop Balanced Amp uses the familiar XLR three-pin (or microphone) connector, with the third line "chassis ground"( not to be confused with the signal "return" line of the audio) that bleeds all noise and distortion to ground. When well-executed the remaining distortion products cancel each other out, which makes for a fastidiously clean signal, and the Balanced Desktop executes this scheme extraordinarily well.

Again, I'll quote the owner's manual: "For you scientifically inclined folks out there, here's the techspeak about balanced amps. Any time an electrical signal passes through a cable, outside (electrical) noise interference can be induced, even when using shielded cables. In an unbalanced system, both the positive and negative halves of the waveform travel together down the positive and negative signal leads and can be influenced by the outside noise. In a balanced system, the positive and negative halves of the waveform are separate; when these separate halves pick up the same outside electrical noise interference, the noise components on one half are out-of-phase with the noise components on the other half (almost like a mirror image). When the negative and positive halves of the signal are combined in the balanced amplifier, the out-of-phase noise components on the two halves cancel each other out as they are combined, leaving only the original, clean output signal ...Translation: superb sound...

Driving headphones in balanced mode effectively delivers twice the slew rate, half the amplifier output impedance, and rids the headphones of significant cross talk due to the common return connection from the drivers."

John Curl phoned me last week. Sometimes he doesn't phone me for months, if he's busy. And he told me what he was up to. I told him about this review and I read to him the above two passages. His comment was: "Tyll is setting the bar pretty high. Those are very impressive engineering and performance goals. Does he deliver?" I said: "Oh Boy! Does he ever."

There are certain headphones, the Sennheiser 600/650 series for one, that have input plugs at the ear-cups. This means you can get the headphones re-wired back to the plugs with Cardas' custom earphone leads, wired to "float" the ground, and employing the XLR connectors. HeadRoom markets an improved Cardas cable with XLR connectors on one end, and the standard Sennheiser connectors on the other. This means, if you employ a digital feed for the source and, as in the Balanced Desktop, the DAC is wired as a "balanced-drive" at its output, there is no access point for your audio to become contaminated on the way to your balanced and properly grounded 'phones. From the DAC output to the headphones, the analog signal is "pure." My lab standard Sennheiser 600s meet this description, as do the XLR-terminated AKG 701 I have on loan from AKG and wired by HeadRoom. More on that anon.

At the height of the Balanced vs. Unbalanced controversy, one of my audio pals (Murray the Z) went to the length of re-arranging the rear panels on his CD player, his pre-amp, and his amp to include XLR connectors. We listened to his best system using both balanced (XLR) and unbalanced (RCA) connectors and there was no appreciable difference. Thinking about that "test" over the years, I concluded the performance of his speakers in his untreated room (with standing waves, nodal points, bass bloom, masking) must have kept us from hearing the small details that are clearly evident through a good headphones rig. I think that listening session convinced me balanced drive wasn't so much better that I had to refit my system, but I was wrong: Murray's room was the determining factor. It also convinced me of the inherent superiority of headphones. If they weren't better, would all the recording engineers use them? There are just too many variables in most listening rooms to manage without breaking most checking accounts, for guys like me.

I have had a similar balanced/unbalanced listening session with the Balanced Desktop. My listening panel (my daughter Rose, who was a licensed broadcast engineer and worked the all-night shift at a local FM radio station while in high school, and my long-time audio-buddy Alan Shapiro) listened to it with the same CD player (an old Optimus 3400 with both analog and digital outputs), the same headphones (Sennheiser 600), while comparing Senn's unbalanced line with 1/4" plug connectors to the Caradas balanced line with XLR plug connectors. Compared with the unbalanced ground scheme the balanced sounded better.

Through the balanced Sennheisers there was an immediately noticeable greater clarity and vividness, with an apparent ability to hear further into the music, to pick up micro-details; and some slight colorations on female voices were removed. There are no lower lows, or higher highs; but there is an ability to hear cleaner, more finely detailed information through a balanced-line Cardas-wired headphone rig. (Good job, George!) In addition, though headphones are not known for their ability to sustain a horizontal image, I got the general feeling of an expanded soundfield. And, in my opinion, even a very fine speaker-driven system can't compete, except perhaps in a dedicated listening room, where most of the echo and masking is reduced to a manageable level.

(The closest analogy I can come up with is to camera lenses' resolving power. I've forgotten the outer limit, but some lenses can reproduce a square inch of a grid with an ever-increasing number of intersecting lines. Some lenses begin to blacken all the spaces at, say, 100 lines horizontal and 100 lines vertical. With some lenses, you can still see the space between the lines at that level. As the number of lines in the grid increases (125, 150, 175, etc.), the amount of space between the lines becomes like ever smaller dots. Eventually, no lens can separate the lines from the dots and everything goes black at, say, 200 lines per inch. I'm approximating all this. It is actually more complicated. The higher the number of lines a given lens can keep distinct, the higher its "resolution." Balanced ground schemes offer higher resolving power, analogous to lens resolving power. And it is most observable as we focus on smaller and smaller units of data, or smaller details in the music. {The path to heaven is in the details. The details are in the Balanced Desktop. The Balanced Desktop is the path to heavenly bliss.} Logic can sometimes mislead. I couldn't resist. Max)

For more exact details on resolution of lenses, see:

Synergistically, Circuits Do Better Than the Sum of Their Parts

If you consider HeadRoom's new features, 1) the Switching-Mode Power Supply, 2) the improved built-in DAC, 3) the improved Home Module amplifier, and 4) the Balanced Line Ground Scheme, you ought to get; 1a) a better controlled, and punchier sound from a 1.35 ampere power supply; 2a) a more SACD-like high resolution circuit built on a 24/192 sampling rate DAC; 3a) a subtler, more accurate voicing of a Walt Jung designed Class A discrete op-amp based amplifier module; and, 4a) greater resolving power of small but important details "down in the mix" due to canceling of plus and minus distortion products by the balanced wiring and connectors. And you can get all those upgrades in the Balanced Desktop.

As set up, my review-sample amp is a super-clean, and somewhat unforgiving piece, capable of recording studio quality. It doesn't use a Doris Day filter to make everything sound prettier. When I get into it, and close my eyes and concentrate on the music, I think it gives the me the closest approximation I've heard to being in a recording studio mixing room. I think I hear down to the brand of the pick the guitarist uses, or how far back stands the rear wall of the recording venue. My review sample includes the Home DAC upgrade, the Home Module amplifier upgrade, and the Stepped Attenuator upgrade, which altogether nearly doubles the price, and is more than a least significant bit. But the sound is outstanding: Outfuckingstanding! Recording Studio Class; Reference setting class; Raising the bar class ...Outstanding!

The Sound

With all these design features, the Balanced Desktop performs at a level I thought only the Millett could reach. For two examples, on a recent recording of Respighi's Pines of Rome, performed by the BBC National Orchestra of Wales, Tadaaki Otaka, cond. (BBC MM277) there is in "The Pines of the Janiculum" (track 12) a dialogue between two nightingales. This is the most hushed part of the piece, and easy to flub up. But it is recaptured and reproduced wonderfully. You might swear they had two birds in cages who spontaneously began singing to each other. The one to the right, by the way, sounds forward of the strings, while the nightingale to the left sounds as if he's in the back with the percussion. Of course they are on tape, and mixed in (as per Respighi's instructions) at post-production. That placement in space is a very subtle thing, and all the parts of the reproduction system have to be spot-on to capture it.

Another surprise was in "The Pines of the Appian Way" (track 13), or the finale. From the misty past of Rome here comes, according to the album notes, "a consular army mounting in triumph to the Capitol. An organ pedal sets the fundamental, and soon distant trumpets join in, and the percussion gradually ramp the tension up towards the cymbal-capped climax." The Balanced Desktop, with a digital feed and through balanced Senn 600 phones, captures the bloom of the cymbals (with the orchestra in full cry), the rise and fall of the clash (as I'm used to hearing it in the concert hall, and through Millett's excellent tubed circuit), the likes of which I thought solid-state circuits usually over-damp . But it does. In my experience, only the best designed solid state designs capture the bloom of various instruments as well as an average tubed design. Tubes bloom naturally. In this instance, the Balanced Desktop also blooms very well.

If the Balanced Desktop can separate all the chaos that is the finale of The Pines of Rome, and the hush of two nightingales singing, keeping all the harmonics and texture of a full symphony as accurately as I've heard, I figure it can handle anything. This is a fine design, wisely executed, small, and with all the usual first-rate fit and finish of the HeadRoom line. It sounds a notch, maybe two notches better than I can remember the big BlockHead sounding. And it is my champion in the solid state category, at about half-the-price of the old BlockHead, most folks' previous champion.

So, if you want to get yourself one of these dynamite Balanced Desktop 'phones amps, you're going to have to perform the magical rites of the Brotherhood of Wild African Dogs (The BWAD?): spin around trying to catch your own wagging tail, yip and squeal continuously, leap up and down, and lick the faces of your audio buddies while twittering, "I dare ya'. I dog dare ya'. I triple-dog dare ya'." Performing this rite will assure the folks at HeadRoom that you are a dedicated headphone listener, and it will test your personal commitment for nonsensical enthusiasms. (For more info on African Wild Dogs, see: Smithsonian magazine; April, 2007).

You will feel all this is worth the time and energy once you hear this amp. Remember "Walkin' the dog?" or "Doin' the dog?" Do The Dog over to your telephone line, phone Bozeman, Montana and talk to someone at HeadRoom. The Balanced Desktop is one bitchin' little beast. I have been waiting decades for the promise of transistorized circuits to be fulfilled, and this amp is a great example of solid-state technology at its best. Warning! HeadRoom's Balanced Desktop Amplifier might cause you to become unbalanced about personal audio. It is a gem, and compared to the tens of $Ks you can spend these days for a strong speaker-driven system, it's still a bargain.

Bargain Time

Everyone loves a genuine bargain, so I would be remiss in my duties if I didn't tell you about the sale at Headroom. I would be withholding evidence which could make me an unindicted co-conspirator. It seems for about $2K HeadRoom is offering one of their Balanced Desktop Amps, plus a set of Sennheiser 650s, rewired for balanced drive with Sennheiser cables, and with XLR three pin connectors they install at HeadRoom, plus a handful of stuff (a one meter fiber optic line with optical connectors, a 75 ohm digital connector cable with RCA plugs, a cable with USB port plugs on both ends, and some other adaptors 'n' stuff), all of which, if you check their price list, adds up to a chunk of change. The amp, with the same upgrades as the review piece, is up to $1700 or more. The Sennheiser 650s are around $450 the last time I looked, and the labor to put XLR plugs on makes the wires worth about $100 more. So we're up to $2250. Now we have to add the cost of an itemized list of all the interconnects and adaptors, and I guess the total will be $100, maybe $150 more. So I'd say HeadRoom is offering about a $400 discount, or about a 20% incentive for serious buyers. Of course you have to send along a digital photo of yourself whirling, jumping, and spinning like a dog, and licking the faces of three other headphones devotees. Just a joke. But I think the Head-Fi website might find it amusing. To check the details of the sale, go to:

I thought I would go into the new AKG 701 headphones for you here. But this piece is already too long. So I'll review the AKGs separately. In the meantime, in between time, if you order the Balanced Desktop Amp, when you call HeadRoom, be sure to tell 'em Max Dudious sent ya'.

Ciao Bambini