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Reviewer: Srajan Ebaen
Financial Interests: click here
Source: Esoteric UX-1, Yamamoto YDA-01
Preamp/Integrated: Esoteric C-03, ModWright DM 36.5
Amplifier: Yamamoto A-09S, Ancient Audio Single Six, FirstWatt F5, ModWright KWA-150
Speakers: Acoustic System Int. Tango R, Zu Essence, Rethm Saadhana
Cables: Complete ASI Liveline loom
Stands: 4 x Ikea Molger with Ikea butcher-block platforms on metal footers
Powerline conditioning: 2 x Walker Audio Velocitor S
Sundry accessories: Furutech RD-2 CD demagnetizer; Nanotech Nespa Pro; extensive use of Acoustic System Resonators, noise filters and phase inverters, Advanced Acoustics Wall & Corner Orbis
Room size: The sound platform is 3 x 4.5m with a 2-story slanted ceiling above; four steps below continue into an 8m long combined open kitchen, dining room and office, an area which widens to 5.2m with a 2.8m ceiling; the sound platform space is open to a 2nd story landing and, via spiral stair case, to a 3rd-floor studio; concrete floor, concrete and brick walls from a converted barn with no parallel walls; short-wall setup against 8-meter expanse and 2nd-story landing.
Review Component Retail: €10.200
Most hybrid amps combine valve inputs and drivers with transistor outputs. Acoustic Plan, Aria Audio, Monarchy, Moscode and Unison Research come to mind immediately. KR Audio stands that time-honored recipe on its head. Their triode output stages are preceded by solid state. Exclusively. Think inputs, drivers and rectification. These Czech amplifiers are further distinguished by who crafts their transistor-ensconced forlorn big bottles. From Audio Research to Zanden, amp makers must rely on various tube suppliers from around the globe. KR does not. They roll their own. Because this firm doesn't fabricate any small glass however, cynics could spot the true reason for the inverted hybrid topography. The late Ricardo Kron would surely have protested. If small signal valves really were superior to the transistors in his circuits, he'd be making 'em. At least I imagine he would have said so. Alas the man passed on. It fell on his wife Eunice to continue operations, on Marek Gencev, Ricardo's protegé, to take the helm as new lead engineer. With KR tradition unchanged, we'll let that fact speak for itself. It naturally applies to KR Audio's preamplifier and preamplifying stages in their integrateds as well. None of those contain any glowing bits (the integrateds in fact aren't true integrateds at all but amps with passive pots). Where most valve amp makers feel invariably compelled to add valve preamps to their lineups sooner than later, the Czechs defy convention once more.
This by way of preamble for e-mailer Brad Morrical: "I would like to invite you to come to Zürich to my apartment for a listen and perhaps opportunity to review a product I'm now
representing in Switzerland (I have hung up my reviewing hat for the time being). I am the exclusive Swiss dealer distributor for KR Audio, a brand I believe you know fairly well. I have on hand the relatively new KR Audio VA350i
integrated amplifier. The VA350i uses the T100, which if you look at the construction appears to be the same as one half of a Kronzilla tube (the T1610 monster tube is actually a dual triode with one stacked atop the other). The sound of the VA350i is very similar to the Kronzilla, much more so than the other smaller models VA320 and VA340. It also benefits from newer transformer design to give it more linearity in the bass by keeping core saturation to a minimum."
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With the only other user of T100s on my radar the Adagio monos from the US arm of Art Audio, this was a pretty exclusive opportunity to sample a one-of-a-kind while perfectly current production tube. What's more, this tube was conceived and engineered for audio use unlike so many other valves in audio amps that were appropriated from the broadcast, television, military or telephony industries.


At about thrice the power of traditional 300B SETs, the 350/350i amp/integrated presented further incentive. Before we continue, a brief note about online reports complaining about KR Audio tube failures whose warranties weren't honored because the latter began with the date of manufacture, not when the customer had actually acquired them. Whatever the implications (if any), onward with today's assignment.

For basic specs, the VA350i offers four inputs; one rec out; remote source, volume and stand-by switching; and, at 3% THD, 30 watts into 4 and 8 ohms. Dimensions are 53.5 x 30.5 x 41.5cm, weight is 36kg. Input sensitivity is 0.75V RMS and input impedance 47K. Circuit topology is zero NFB single-ended and thus, class A. You might demur "of course" but premiering at the Rotterdam Doelen Lente show in April 2009, KR introduced its first push/pull amp using 2 x KT88 per channel. The VA350's J-FET driver stage is said to be identical to the Kronzilla, a further reason this model is informally referred to as Baby Kronzilla. Output impedance of 4 and 8 ohms adjusts via set screws behind a litte cover on the back panel. XLR inputs and phono input are optional. Response is 20Hz to 40kHz -3dB, S/N better than 100dB, 230V/50Hz power consumption 300 watts. The German importer's brochure lists a 4-year warranty on the electronics and 2 on the valves. Web info elsewhere claims half. That is a very significant discrepancy. Did anything get lost in translation? Another discrepancy exists for the input sensitivity. It is listed as 0.75 and 1VRMS respectively.