It's now May, I'm back from my New Zealand/Germany trip, I'm not moving to Kiwiland though it's stunningly gorgeous (but a bit stuck in a time warp where cultural infrastructure goes) and the plot of this review thickens. To the list of ex, not deplorable options, we now add the $595 Antique Sound Lab MGHead DT/OTL 32 headphone/preamp that's landed in Taos since. Like Chazz, it provides both standard 1/4" and Canon-style AKG K-1000 outputs. Like Chazz, it employs tube rectification but via a 5AR4, then uses twin EL84/6BQ5s per channel while offering an extra three inputs, twin outputs and a tube cage. Naturally, the ASL unit will get its own review. It merely makes appearances now for comparison's sake. After all, such an unplanned opportunity of fortuitous timing doesn't arrive every day.

Since we've got a lot of ground to cover, including potential confusion while sifting through the countless amp, tube, triode/pentode, headphone and cable options, I'll abstain from the usual descriptions of how I arrived at certain observations. I'll merely state the conclusions below relevant headers for a terse results-oriented approach. With both amps benefitting from Harmonic Technology Fantasy 10 power cords plugged into a Furutech eTP80, their respective tube pins were carefully treated with Walker Audio's SST SuperSilverTreatment. Tube lovers, take note: This is de rigeur and completely silly in both effectiveness and expense. Alas, for the ultimate, you should first use fine-grit paper and sand off the pins which I did not do since the tubes weren't mine. With that covered, here goes.


AKG K-1000 drive: Chazz vs. OTL 32
In stark defiance to output power/drive expectations, the ASL unit with its lo/hi gain switch provides significantly more gain and headroom for the power-hungry Austrian earspeakers. It makes the ASL/AKG combination an unqualified functional recommendation that's completely independent of software recording levels. If you need more volume than the four 6BQ5s deliver so readily (though very surprisingly, I might add), you've already lost more hearing than is healthy. Conversely, even in ultralinear mode (which, on 74dB/1m sensitivity headphones, amounts to a smaller power boost than you might think) Chazz can run out of steam especially on classical recordings. Whether and how often this could become a limiting factor will be a matter of your software collection and listening habits - it'll just refuse to get louder when you have finally bypassed the attentuator; not necessarily a bad thing. Still, it's fair to mention that K fiends looking at Chazz should ascertain this situation before committing to a purchase.


AKG K-1000 sound: Chazz vs. OTL 32
Running Chazz in ultralinear and on cryogenically treated KT88s (my favorite setup with these 'phones), the most overt sonic difference was a somewhat tighter, more precise delivery on part of the OTL 32. Chazz rendered the same tracks a bit looser and softer around the edges. This was similar to how moving deeper into the farfield with free-standing speakers changes both apparent perspective and articulation. Clearly, the K1000s' major trump card is their phenomenal spaciousness. It generates by far the highest amount of out-of-the-head quasi soundstaging from headphones I've heard. It literally wraps around your occipital especially when the ear pieces splay outward for enhanced inter-channel crosstalk.


The extra infusion of apparent space Chazz's less tight-fisted mien introduced could strike some listeners as slightly diffuse, a bit remote or simply more relaxed. One could assume that most if not all of this phenomenon might simply be explained away as a function of power delivery. Tough loads always pull together tighter and operate more precisely when fed more power. Call it control. The ASL sounded as though it controlled the AKGs better. However, inferring that Chazz sounded out-of-control would be incorrect. It simply amounted to the audible difference between driving electrostats with excessive power to make them more dynamic if perhaps less airy and diaphanous. But since very similar observations also held true for the Sennheiser HD600s, I'm inclined to write off raw control as the chief contributor here.


Senn HD600 sound: Chazz vs. OTL 32
Call this a rerun of the prior paragraph though less pronounced and still on KT88s. With overkill headroom on both amps, these differences now could no longer be lain at the feet of output power but rather suggested different circuit voicings per se or tube-based signatures. The ability to switch output tube types in the Chazz would add further variables taking as their baseline the circuit's inherent 'voice'. For the purposes of comparing the KT88-outfitted Chazz against the OTL32 with stock Sovtek EL84 and JJ 12AU7s, the prior softer vs. more articulated connection still held true. This didn't seem to have much if anything to do with timbre (as you might expect when thinking THD and tubes) but rather, edge definition or focus. Simply, the ASL amp locked things into place a bit harder which became most noticeable on tracks with plenty of congested accompaniment in the background. It further separated and clarified things in the rafters, behind and removed from the spotlighted soloist. Think of it as slightly enhanced emphasis on leading edges vis-à-vis the DIYCable amp.


While protracted late-night listening sessions would likely have unearthed further distinctions of progressively finer-gauge hair-splitting if the main focus of this review had been a head-to-head comparison between these units, the primary distinctions were limited to the arena described. In other words, nothing of earthshaking import, no vanilla/strawberry gap of occupying opposite poles. The ASL amp is $200 less and can double as a preamp. The Chazz uses thicker sheet metal, a wooden fascia, looks better to these eyes and, because of its output tube options, can be more comprehensively tweaked to conform to its owner's liking. As an AKG owner, I'd undoubtedly pick the ASL as the more optimized gain match. If I owned Grados or Sennheisers, I could go either way and be a very happy camper indeed. Now let's raid the spice patch as offered by EL34s, KT88s and 6550s in the Chazz.


Output tube flavors with Senn HD600:
The EL34s were the no-contest winners here. They sounded more accurate and resolved, open and lit-up without being bright in the least, demolishing the KT88-based perception of looseness or lack of articulation. By comparison, the kinky triodes seemed veiled, distanced and a little dense and murky. The 6550s too lost a bit of immediacy and incisiveness to the EL34s and in general appeared to be less refined. The EL34s had energy without bite, cleaned the window with undiluted ammonia and removed whatever slightly opaque barrier both 6550s and KT88s erected between the music and the listener.


Deciding between the Valve Art and Svetlana pairs I had on hand was harder but the eventual nod went to the $8/ea. Valve Arts for combining clarity with a modicum of warmth and creating a very becoming balance between energetic drive and elegant demeanor. From Oscar & Co.'s French Salsa to Lila Downs' nuevo Mex, from Jan Garbarek's Visible World to Karsh Kale's edgy Techno, with a few Pavarotti and Carreras crossover numbers thrown in for good measure, then on to Cheb Mami's forward Raï, Paolo Conte's laid-back gravelly Italo Swing and one of my all-time favorites, Dulce Ponte's Lágrimas, the Valve Art'd Chazz in ultralinear simply made the Sennheisers sing. Triode was a little sweeter and demure but also slightly fuzzier. Being sometimes accused of mating robustness to darkness, this pentode EL34 pairing showed the famed Sennheisers to be robust but well lit for a thoroughly engaging, utterly non-fatiguing presentation.

Because the HD600s are rather endowed in the bass department, ultralinear operation provided additional control to combat what otherwise might be dubbed slightly plump especially when compared to the K-1000s which, while punchier and drier, can't convey the kind of weight and ripe bloom the Sennheisers manage. Naturally far more important than my personal fancies was the simple fact that tube rolling and the Chazz not only go hand-in-hand but are mandatory and fun to mold final sonics into your preferred shape and color. Needless to say, this includes the rectifier and driver valves as well.


Before we explore the Cardas and Stefan Audio Art replacement wire harnesses versus their stock equivalents, a second reminder that treating tube pins with Walker's silver-based contact enhancer really does bestow very appreciable benefits that you should harness no matter what tubes you end up with. This isn't a shameless plug for wily Walker but a cheap tweak with legs - it goes farther than you might think. Treating your various other connections while you're at it will come natural and without prompting. It'll simply prove to you without a doubt that the little things truly do matter - especially when transducers are parked right on top of your ears to really let you hear who's boss. This includes tube dampers. I'll have things to report on the Dutch Duende Criatura units (Teflon rings with Titanium spring tensioners) while our own Stephæn bought Herbie's Labs dampers and has a hard time coming to grips with their potent effects on his Art Audio PX-25. The Criature critters I had on hand fit the small-diameter tubes of the ASL amp but not the stockier valves of the Chazz. I've just ordered some for my Audiopax KT88s and additional units for the Zanden DAC to take the full measure of Duende [Flamenco-speak for beyond-the-mind inspiration]. Stay tuned.