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Sound basics: Getting acquainted with Valhalla first over audio-technica's very easy ATH-W5000 'Raffinato' load—volume at 12:00—the initial thing to notice was a particular crystallized clarity wedded to nice elasticity. Successful valve circuits tend to be good at elasticity. I doubt it's measurable by test kit but the ear does recognize it. Take Gurdjieff's Chants, Hymns & Dances with Anja Lechner & Vassilis Tsabropolous [ECM]. It's minimalist cello and piano stuff that ebbs and flows with mondo rubato. It's the antithesis of metronomic marching-band rigidity or juju slam. It's about twilight, pastels, dying fades, tone modulations, breath. In the temporal domain, the Asgard's basic attitude to the same material was less gushing and more contained. This you'd expect if you're familiar with basic differences between competitively good transistor and non-feedback tube circuits.

More unexpected—less so in hindsight considering bandwidth and concomitant low treble phase shift—was the crystallized aspect of tintinnabulation. Nelson Pass first turned me on to that term. I had to look it up as "the ringing sound of bells or similar jingling tinkling noises". Voilà. A piano's upper registers can get tinkly and disembodied; or weighty but somewhat dull. To get both tinkle and weight is tricky. Most tube amps will err on the side of weight. Actually that's often a sign of insufficient bandwidth and some phase fuzziness. The Asgard goes more for tinkle. The Valhalla had just a bit more weight but otherwise tinkled splendidly. That's the crystalline element of clarity, glass, metal, light refracting off water. Glassiness per se would go too far but the Valhalla on the Raffinato did not. If you expect or desire more orange or gold and less white or Platinum; something more subdued, soft and girthy... these Russian tubes won't do it.

Case in point was "please don't" fare which in our household equates with Balkan Messengers. My wife can't stand this unhinged angular Bulgarian/Macedonian stuff. It fries her nerves. Its odd-metered forms go by names like kopanitza and ruchenitza (Ivo Papasov remains the uncrowned king of breakneck-speed ruchenitzas to have been much admired by Frank Zappa). It's neither pretty nor easy. Call it acquired taste. Nalbantoglu's violin scratches and jars more than it sings. The drum kit cracks and rolls. The bass pops and growls ominously. Neshev's accordeon pierces.

It's devilish rhythms and extreme chromatics undergoing strange progressions with very few melodic garnishes - and most of it at high speed. It requires a kind of mind suspension to enter a still space before one fully appreciates the very advanced nearly otherworldly mastery involved. (I never get whatever frequency Free Jazz is on. I lock on fine to Bulgarian wedding music. Go figure.) The point is, the Valhalla didn't prettify a thing. In this context that's praise, not whining. Where this affordable piece missed out on the big time was in just how brutal it could crack and cut. For that one might need a fatter power supply. It would mean that bass transients peel out fully to slice, dice and rumble whilst being completely backed by dense mass. This relies on speed (present) and follow-through (not fully present).

My 8-watt tube-rectified optioned-out Woo Model 5 300B amp does more weight across the board but is also softer and tonally more 'enhanced'. Its world is more orange warmth and redolence. As such the Valhalla doesn't really comply with related notions. It's leaner, faster and more lit up. In fact it's not much different from the Asgard. This extends to how the upper midrange—the so-called presence region—is handled. Both machines are slightly forward. Depending on load, the Valhalla was the spicier of the two. Particularly at higher volumes this could get fatiguing at first.

Looking at Schiit's specs, the Valhalla's most efficient power transfer occurs at 300Ω. There it makes half a watt. Figuring I'd hit its sweat spot with my 400Ω-rated Sennheiser HD800, I advanced to 2:00 on the dial to match the Raffinatos. Slam and grippiness increased. What also snuck in was a completely unexpected drier demeanour and a faint sense of associated brittleness. beyerdynamic's 600Ω T1 wanted 3:00 on the control to match levels. Now warmth increased but I felt sibilants on brighter Pop fare were slightly overcooked (that's mostly how they're recorded - again no leading lady soft focus). AKG's K-702 pushed the dial to 4:00, the planar magnetic Audez'e LCD-2 pretty much maxed out available power and started to fray around the edges. As I turned up the thumb screws—by using headphones that turned out to be less than ideal loads—things got glassier and more tiresome.

These first impressions were compiled with iPod AIFF/ALAC files via Sieben Technology dock. My overriding sense was that the three letters OTL conformed to my—personal, unreasonable perhaps but nevertheless active—prejudices of speaker-level OTLs: fast, fast, fast; harmonically too white; insufficiently weighty and massy overall to compensate. In short, an electrostatic aesthetic. Lots of spittle, teeth and throat, less diaphragm, not enough anchoring through the feet into the ground. I didn't hear any drive issues with the big Sennheisers but neither did I feel that personalities of ear speaker and amp were terribly well matched. Too much like meets like. Perhaps I needed a better source? What would be reasonable for a $349 amp? I'd use the battery-powered Cypher Labs AlgoRhythm Solo. That outputs a standard 2V max through its 3.5mm stereo jack and grabs the digits off the iPod in asynchronous USB master mode, then forwards them via internal I²S protocol to Wolfson's top 24/192 chip. I had a quality Zu Pivot 3.5mm-to-2xRCA link for just that purpose. Or did I need more run-in than Schiit had put on the circuit and valves? Time to step away, cycle the iPod on shuffle through its 4000 tracks and hope for the best.