This review first appeared in the 6Moons.com magazine. You can also read this review HERE in its original version. We publish this article in a mutual syndication arrangement with publisher Srajan Ebaen. Everyone can write to him – if you have questions or wish to send feedback – you’ll find an e-mail address under his name. All images contained in this review are the property of 6Moons.com. - Ed.

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 nowre presenting 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."

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. As a ferociously hot-burning tube -- the far smaller 6C33C can take dissipation lessons -- the T100 on this amp benefits from a heatsink chimney with solid top plate to which the valve is literally wedged from below with an inset rubbery cap.

Apparently deliberate, this chimney is a pain to remove. It doesn't come off in one piece as competing designs manage with banana sockets. The three master rods are instead bolted firmly to the steel cover. Then each stand-off between metal ring to metal ring screws individually to the master rod. To remove a T-100 without the cover is possible. There's a larger spacing between the rings half-way up. However, it does require a bit of dexterity and fumbling. Naturally, one then also pulls out the valve by its glass envelope and not the base as is usually recommended.

Elephantine by 211/845 standards, the T-100 is dwarfed only by its double-decker T1610 stable mate. An unusual construction feature is the inverted glass nipple built into the thick glass envelope on top. It centers the internal metal assembly and prevents any possible rattle, move or eventual Pisa stunt during the valve's quoted life span of 10,000 hours.

Like its Czech cousins at Euro Audio Team and Emission Labs, this bottle's build quality is extremely stout and tank-like. The same applies to the amp. Its black-paint octagonal output transformer covers are potted, the larger one with the toroidal power transformer and filter choke behind it is not but vented out the back.

Additional heat sinking flanks the cheeks but barely gets warm unlike the output iron. The tube chimneys themselves go infernal and can't be touched for more than a split second. They morph into true space heaters and are a natural-born nemesis to air conditioning units, tropical climates and kiddie fingers.

Lovers of long-wearing deep chrome will be disappointed by the scratch and stain prone polished steel deck. Over time, it will never again look as perfect as it did upon delivery. In these elevated leagues, that's a consideration.

The included remote works fuss-free but is of the generic plastic type and here joins the general cosmetics by not winning marks for high style. Everything is functional and of true substance but accompanied by an industrial, somewhat drab utilitarian specter that's outshone by most of China's present imports.

The innards show widely spaced circuit boards connected by standard flying leads and ribbon cables. The inputs are relay-switched, the auto bias is microprocessor controlled.

The liberal use of micro processing in a no-feedback single-ended triode amp demonstrates further that KR Audio's chief designer Marek Gencev has little patience for the nth stock iteration of old-timey me-too SET concepts.

Parts quality seems solid but non-exotic. The critically important output transformers elude normal inspection of course and are KR Audio's own.

Unlike the servo-biased Ancient Audio Single Six 6C33C monos with their deliberate 3-minute turn-on delay, the VA350 snaps into action surprisingly fast as indicated by the power LED going from red to green. Flashing red would indicate lock-down by the protection circuitry and most likely tube death. While the master mains sits on the rear, the frontal (and remote-activated) stand-by switch seems to effect a pretty comprehensive power-down. It will likely become the de facto on/off control for all but the first session.

Here are the relay-switched four single-ended inputs (XLRs can be custom-ordered).

These are the external accessible impedance-setting screws at 4 ohms. 8 ohms requires that two screws occupy the center positions and the upper and lower positions be vacated.

Here is the motor-driven blue Alps pot flanked by the 4-pin tube sockets. The T100 runs two smaller and two bigger pins. Beware proper orientation. The wood-crated amp of course ships with the tubes installed so this refers only to eventual tube replacement. As expectedt from its S/N spec, the VA350i betrays no transformer hum, tube hiss or other audible indicator that its output devices are one-of-a-kind, over-dimensioned vacuum tubes. Brad Morricab, Swiss satellite dealer of the German importer Dipl.-Ing. Andreas Milkovits at Ami-Hifi.de, drives big Accustat panels with this amp. He reportedly has not encountered yet a 'normal' speaker beyond Baby Kronzilla's grip.

When I first took receipt of the VA350i, it retailed for €8.300. Two months later, the price was raised to €10.200. That's far from insignificant. For €10,000, you can buy a pair of 130-watt Octave MRE-130 monos with better finish, four times the power and as we'll see, superior performance. For €10K, you'd also expect Burmester-quality chrome, not discolored 'stainless' steel. And you definitely should expect an active preamp stage rather than passive pot (yes, Baby Kronzilla sounds demonstrably better with an outboard preamp - Esoteric's C-03 set to zero gain proved the point).
To my mind, the VA350i occupies a very tough spot in the middle of no-man's land. From a power perspective, it sits between the 45/2A3/300B direct-heated brigade; and real bruisers beyond 100 watts. Listeners with speakers suitable for group N°.1 won't buy into the notion of needing more power than their low-power SETs provide - unless of course the VA350i made an unavoidably persuasive sonic argument to "out-300B" real 300Bs like the Emission Labs 300B XLS in my rather cheaper Yamamoto A-09S. It does not. It's flatter, more staid, damped and fixed, lacking the inner fluidity and glow of the A-09S. Additionally, over my 98dB Rethm Saadhanas, the VA350i was noisier. For just $2,500 and on the Rethms, the FirstWatt F5 was clearly superior, a far better buy and its transistors sounded better than the pseudo transistors of the big KR tube (I say pseudo since they sonically lean in that direction).

In short, the VA350i is no 300B-on-steroids replacement for ordinary but first-class 300B amps or equivalents. It's rather drier and more reined in by comparison. This continued to be the case over my 91dB ASI Tango Rs whose perfectly flat 6-ohm impedance below 1,000Hz makes them a dream load for high Z-out amps. The KR amp again sounded more solid-statish yet could not match the low-level resolution, depth layering and bass control of a real transistor amp like the ź-priced F5. I was beginning to suspect that cruising for a truly convincing must-have rationale for this amp would prove difficult in Casa Chardonne. I was right.

On the other side of no-man's land are the listeners of group N°.2 who own '100-watt plus' speakers. They won't buy into the KR's 30 watts either. While the VA350i's drive really is unusually stout -- my 85dB/4-ohm Mark & Daniel Maximus Monitors with upfiring omni AMT would make the point -- the push/pull pentode/feedback Octave monos had more precision, clarity, low-end control and articulation (i.e. far lower output impedance) than the no-feedback single-ended Czech. The meaty Zu Essence did mate well with the Baby Kronzilla for a well-damped yet still buxom sound but knowing how spectacularly well this speakers works off far cheaper amps rather put down any mondo-valvular excitement and the flag on half mast.

So far, my no-man's zone statement had found that from a performance perspective, the VA350i was neither as suave, holographic and sinuous as rather cheaper amplifiers fully embodying the usual reasons why folks go SETs; nor quite as robust, dynamic, colorful and load-invariant as real push/pull tube muscle amps priced the same. This second half was assessed by moving out my regular transducers and drafting into service the synthetic marble monitors of the compact but serious Mark & Daniel assault at big full-range sound from a small box.

Obviously, the low-profile German tanks standing by did not merely pack heavier ordinance. They also are monoblocks with truly dedicated power supplies per channel. And for those desirous or in need of full-on 2-ohm happiness, Super Black Box capacitance banks can be added optionally without any modifications but a simple plug & play connection of an umbilical. For these tests, I did not add those silver boxes but ran the MRE-130s 'unfortified, au nature'.

It quickly became clear that this was rather more the kind of speaker Baby Kronzilla longed to drive. To get out of first gear, the load had to tickle it into action and these synthetic marble boxes with curved AMTs performed the wake up call. But output impedance being what it is, the Octave monos had even more low-end control, crunch and brutesse (to coin a term combining brute force with finesse) and overall better articulation and clarity. The KR suffered a bit of fuzz or indecision by comparison and lacked ultimate grip on the lower frequencies.

The completely mindboggling potential of the latter is a calling card of this particular speaker. Arguably voiced bottom heavy as though designer Daniel Lee meant to impress upon us the utter improbability of enclose size and woofer diameter producing such output and extension, my original pre-Plus version really benefits from the counter balancing output of the optional upfiring AMT above 3kHz. Then it's a quite linear speaker with shocking spunk.

Alas, if I had €10,000 to spend and owned speakers like these (expand their category to include larger multi-way floorstanders like Aerial, Dynaudio and Thiel), I'd unhesitatingly recommend the Octaves over the KR. It's an altogether more reasonable proposition. If I had speakers like the previous three, I'd not recommend the KR either. If somebody wanted a high-class text-book SET sound, I'd steer them to the Yamamoto or Emillé Labs equivalent with nice spare change in the pocket. If somebody wanted higher resolution still, even better noise performance and was willing to sacrifice some tone density, I'd point them at either the F5 or F3 in the Nelson Pass FirstWatt lineup while saving our imaginary shopper some very serious coin. And yes, you would need a preamp. But then €1.150 for something like the Trafomatic Audio Experience Head One already outclasses the passive pot in the VA350i.

These might seem heavy-handed statements but the overall state of the economy demands an unflinching look at the bigger picture. All around there's less room for excuses, for excessive spending, for running hot as sin, for not being fully competitive to make a persuasive argument to any well-informed shopper who is careful with her money. This does not invalidate KR Audio's achievement of an unusually powerful SET with a proprietary output bottle. But for what it is, it's become too expensive. More importantly perhaps, it's a peculiar case of neither fish nor fowl. Those willing to buy into this type of inefficient operation with its huge dissipation of heat into the room will want more tube-typical audible traits to sweeten the bargain. Those wanting real power but tubes will go for Octave or VTL. Everyone else has endless choices in transistor land. Where does that leave the KR Audio VA350i? I'm honestly not sure.

Quality of packing: Delivered unpacked by Swiss importer.
Condition of component received: Stainless steel showed discoloration and scratches from normal use.
Completeness of delivery: Includes power cord and full-color brochure. Tubes arrive preinstalled.
Website comments: More product information and better photos would be welcome.
Human interactions: Quick responses from the Swiss importer.
Pricing: With the recent price increase, no longer competitive.
Application conditions: Unusually potent SET that will drive speakers well beyond the 300B brigade. Sonically, it's no stand-in for 300Bs but veers more into solid-state sound.
Final comments & suggestions: Should include active line stage and better finish on the pseudo-chrome polished metal chassis. A more convenient tube cage removal solution would be nice as would be biwire terminals.

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