Barking up the wrong tree? Lady Circumstance wrapped the Lio DHT review just before the White Knight got busy. This conclusively settled an old but basic argument. At least in my experience to date, the only way to make transistor amps sound like proper tubes is with direct-heated triodes in the preamp stage. But not just any. Vinnie Rossi's is a spud circuit. This means no driver tubes, no output iron. It does mean 500kHz@-3dB bandwidth with stock electro-harmonix Gold Grid 2A3 bottles; and zero noise! This rare affair potentizes the languid, fluffy, spatially huge triode aroma well beyond personal ownership takes on Art Audio's PX25, Yamamoto's 45 and 300B amps and Woo Audio's 300B monos. The only real exception to that lot had been my friend's Berning Siegfried. That sounded fundamentally different.

The Lio trick is still other. Any proper transistor amp will transcend typical SET limitations on bandwidth, driver control hence bass grip, distortion density and SN/R. What the DHT spud + transistor amp combo does is distill, concentrate then dominate with what's best about direct-heated triodes. This eliminates all of their weaknesses. So it is still not the same. It's better. It even works with solid-state amps of Job 225 or Crayon CFA-1.2 stripes as just two of their kind I tried [Crayon setup below]. Obviously truly ideal SET/speaker mates can downplay or perhaps even entirely overcome typical SET limits. It simply requires very specialized transducers. This seriously narrows your window of choices. Meanwhile Vinnie's spudster pulls off that stunt with arch-normal low-efficiency speakers using ceramic drivers. Tube wranglers, put that on your breakfast menu!

All this by way of saying that the White Knight couldn't duplicate that effect even with our tubed Fore Audio DAISy1 DAC and tubed Nagra Jazz preamp in the loop. 12AU7/6922-type small triodes won't give off that special DHT aroma no matter how much you might like them to. Given Lio's powerful proof to the contrary, Alexey's amp really had to be judged as a transistor amp, never mind our two-page back story. In the sweat spot, none of that mattered. The White Knight sounded like a transistor amp. Battling our XA30.8 obviously set very high standards. If the S.A.Lab ended up not being their full equal, it should actually be expected, never mind its 30% higher tariff. Nelson Pass has plied his specialized craft for more than three decades. Today he's called a legend in it. Alexey's core expertise is valve circuits. He hasn't yet put in the same transistor time. Regardless of advertised quality, could his output transformers really be better than none?

TIme to progress from back to front story. To reshuffle the deck accordingly, the Lio DHT was benched in favour of the D1 DAC/pre from COS Engineering. Though a fully balanced deck, it would run both Pass and S.A.Lab single-ended to use the same cable into the latter's direct-mode input. This signal path was pure solid-state.

Pass Labs XA30.8 vs. White Knight. The core difference here was about a pervasive softness associated with focus and grip. The Russian played it more polite and gentle/genteel. This was a full-bandwidth effect but perhaps most dominant in the bass where the American exerted more apparent woofer control for more profundity and foundation anchoring. Whilst not affecting subjective soundstage perspective, the White Knight sounded more distant and farfield because of its minor vagueness. The XA30.8 sounded more powerful with the usual things this entails: more propulsion, drive and forward communicativeness; more firmness, substance and slam when called for. This offset still enlarges when COS D1 and Pass connect via XLR (which merely is an observation about how they interact, not about either sounding better in RCA or XLR mode).

Tonal balance was very comparable. This parked the White Knight in the same general vicinity of minor darkness and warmth which distinguishes the Pass from our resident Crayon and Job 'speed' amps. If you insist to assign this twin constellation of qualities—the second being a more distanced attack behaviour—to tube sound, the White Knight certainly belongs. It's simply not exclusive to valves nor true for premium DHT implementations. To reconnect with damping and regardless of its output impedance, the S.A.Lab sounded less damped than the grippier Pass and in fact, slightly underdamped. Whether or not this was due to the output irons or stepup transformer I couldn't say. I will say that prior experiments with transformers for voltage gain did share some of this more limpid de-stressed gestalt which bleeds out a certain toned tension.

That can be a key ingredient for the row 15 symphonic perspective in a very large hall. It's not for a close-to-stage club performance or most hard-hitting modern music for that matter. From this one suspects that Alexey used classical music and its general perspective as the overriding design reference also for his transistor amp.