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As it turned out, quite close. But close is no cigar. And no cigar meant other than same. To make swaps instantaneous I ran my Metrum Hex with metal Y adaptors so both amps saw signal at all times. With volumes matched I could plug whatever can I wore back and forth ad infinitum. I left one unused can in the tube amp to load its output iron. I kicked off with ALO-rewired Audez'e LCD-2 followed by equally recabled beyerdynamic T1. The Bakoon HPA-21 ran in current mode since that's its forté. The Studio Six ran on stock tubes. Comments on rolling an included alternate set would be separate. With Bakoon having garnered the first Blue Fingerprint Award (an amalgamation of our own Blue Moon Award with Polish contributor Wojciech Pacuła's equivalent Red Fingerprint as a joint award from us both), the Portland challenger had high to reach. Which it did.


Where it remained distinctive was with its fluffily aerated quality. Energized space. Oscillating molecules. The Studio Six felt and sounded grand. Exuberant. This was a big-picture approach in which all the small detail was embedded. The HPA-21 felt intense in a high-contrast sense of keen focus. It highlighted the simultaneity of massive detail. The big picture was there to relax into. First though came the contents which the big picture framed. To exploit a familiar visual, one presentation proceeded from forest to leafs (the valves), the other from leafs to forest. Same difference? True, both viewed the same scenery with a similar sense of lighting though ultimately the Bakoon's overall illumination was higher. Even so the Studio Six felt spatially more expansive. The Bakoon was more compact. The former was texturally a bit looser and softer. The latter played it tauter and with higher contrast. Connective tissue between sounds tied them all together. Studio Six. Their bone-like cores were cleanly separated. Bakoon. These are stylized attempts to pin down a different feel. It was obvious and simple in the experience. It's less elegantly simple and obvious in the verbal translation.

Both machines would seem to operate at the top of their respective technologies. This nearly distills and thus condenses their two gestalts which followers are only too familiar with. Here they became fine textbook expressions, not caricature excess. Surprising if logical was that this placed them on about the same level. Equally compelling, wildly divergent on price and size. On the latter points the Studio Six was clearly disadvantaged. It's far bulkier and costlier. Its tubes will eventually need replacing though so too do Bakoon's batteries. For $3K the small HPA-21 doesn't look like much. For $5K the Studio Six seriously looks the biz. On sound, an innately voluptuous slightly dark rich headphone like the LCD-2 moves a bit more in that direction with the Studio Six. Think highly resolved opulence. A more linear drier can like the T1 hones its own microscopic chops with the Bakoon. Strategic matching combines like with like for maximized flavor; or cross dresses to split the difference. I gravitated toward the latter. Audez'e on the Bakoon. Beyer on the Studio Six.

The ST6 was shockingly quiet. With valves you expect some noise. Whatever noise the Studio Six made vis-à-vis the Bakoon, I could no more hear it per se than my big rig makes noise when the music stops and I walk up to the speakers. Given how noisy the oft applauded Leben is as headphone amp, that's big chapeau time for Studio Six designer Thomas Martens. Though his 6SN7/6V6 valve combo suggests big tone, I didn't hear it in any compound fashion of extravagance. What one associates with valve virtues and liabilities—midrange centeredness, softened transients, weighted decays, denser textures, oversaturated colors—here existed only as faint echoes. By contrast with the Bakoon, I would cite a minor reduction of energy in the brilliance region. This had a concomitant effect on the overall sense of lit-upness. But I couldn't say the same about the opposite end. The Bakoon was arguably grippier but the valves played it slammier. Bass hounds should sit up and wag tail. Such a potent well-grounded foundation underscored the already generous sense of space. As anyone with a quality subwoofer knows, infrasonics are less about bass per se and far more about scale, depth and richer colors. And that's the kind of heat the Studio Six packs. It's a from-the-ground-up sound.

Whilst it reads perverse—a big symphony orchestra crammed into your skull—large-scale classical like Antonin Bruckner came off unnervingly well. This the ST-6 did so well that I pigged out on Leoš Janáček's Taras Bulba and his martial Sinfonietta which for its fanfare sections adds to the usual woodwinds and strings nine C trumpets, three F trumpets, two B trumpets, four trombones, two tenor tubas, one bass tuba, kettle drums, tubular bells, cymbals and harp. Check out this Youtube vid for a taste. It's far from my favorite performance but does properly show off the oversized brass section. Little else visualizes as well what kind of bombast the Studio Six is good for. Now remind yourself that we're talking about a headfi amp. This should have the proper gears click into place. That's the kind of player the ST-6 is. And remember. Whatever Janáček you may have just heard over even the snazziest desktop rig will have been 256kbps crap vs. the goods the Studio Six delivers from a proper 16/44.1 file. No comparison!

For the money the Bakoon is the unequivocal choice and in addition puts two parallel flavors on tap with its voltage and current outputs. Were money no object? Now the Studio Six beckons with a similar if not as extreme level of resolution whilst expanding on dimensionality, airiness, bass bollocks and musical interconnectivity where the HPA-21 separates harder. Even running 24/7, the ST-6 doesn't get warmer than mildly. It's clearly massively overspec'd for the actual task at hand. That's the overall gist and attitude.