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KR Audio VA350 integrated amp

ReMusic Spark Award

To ReMusic Spark Award introduction

Have you ever heard what a tube amp can do?

How long haven’t you enjoyed the richness of a tube amplifier?

Have you ever listened to a real tube amplifier, haven’t you?

Seek immediately a KR Audio…


Czech Republic, Prague, 2012. KR Audio is a worldwide manufacturer of tubes and tube amplifiers. “Worldwide” in every respect. They manufacture tubes with total commitment. Some of these are unique both as design and as production. KR Audio has been crossing the history of tube manufactures indeed: we will show it in a next review dedicated to this brand, not so famous here in Italy, but incredibly appreciated where… people can afford it.

KR Audio started its production in the “Roaring ‘20’s”, the prerogative years of Philips’ brand, although the existing company was founded twenty years ago, thanks to the competence and enthusiasm of Eng. Riccardo Kron. I am proud to say that he was my fellow countryman: Piedmontese from Susa Valley and last heir and Executive of the local and historical Magnadyne factory, famous manufacturer of valve radios. Nowadays, KR has been running by his partner, Eunice Kron, a person totally committed to Riccardo’s memory and to increase the value of the huge historical and cultural inheritance of his work.

One of the most successful and important choices recently made by KR Audio has been hiring young and skillful collaborators in order to assure continuity and a long lasting future. Although the company is small, their standards are very high. Each operator, starting from the designers, has his own unique competence.


Happy birthday, KR Audio. Good luck, dear Eunice.



In my listening room, and not only here, I have had the honor of long testing one of the most significant devices of the brand: the KR Audio VA350 monotriode Integrated Tube Amplifier. This “apple pie” - seeing that my mouth waters at its listening - is a massive integrated amplifier, albeit with only 30+30 Watt RMS.

The VA350 is huge (but not gigantic), compact, stout: just as we would like to imagine a bit retro’ amp with up-to-date performances. The cabinet is metallic, with a black orange peel varnish finish and a thick glass envelope on the top where tubes and transformers mirror themselves.

The heat sinking flanks are just decorative, since the warmth that heats your listening room comes from the tube heat sink towers - in pure Fritz Lang’s Metropolis style - and from the transformers, in particular from the input ones (less from the output lateral ones). The towers also do as a protection for the tubes and slightly push them in the right position with a damping and heat-resisting o-ring put on their apex.

A microprocessor controlled auto-bias circuit controls the output tubes. When the power LED is green the amp is working, and so are the tubes.

A small precaution: the amp turns on with the slightest touch at the input selectors, so pay attention to the naughty fingers of your kids or to the feather dusters when you act as a housekeeper.

I was almost forgotten the WBT and RCA output connectors for the rec out.


Class A monotriode, zero feedback, it adopts intentionally a hybrid circuitry. As confirmed by the head designer, Eng. Marek Gencev: “Our amps are hybrid. We try to join at best the two worlds, tubes and solid state. The preamp stage uses J-FET and the driver stage MOSFET. The SET with their output transformers are only in the final stage of the amplification. We do it in order to obtain a “tube-like” sound with the highest possible signal to noise ratio. Also the manufacturing technique follows the specificity of the components. The solid state stages are assembly on circuit boards, while the tube stages are air-wound. The reason is obvious: every circuitry has its own soldering technique”.

The splendid T-100 power tubes – with a great workmanship – utilize the same transformers of an 845 but with different voltage and current on the filament, with a MTBF, Mean Time Between Failures, of 5,000 hours.

The power absorbed by the filament is one fourth. Therefore, the performance is lower but with a great reliability: less efficiency for a longer life. From a musical point of view just image most part of the power of an 845 tube jointed to the grace of a 300B: this is for me the KR T100.

It is odd that the company does not report the signal to noise ratio of any of its amps: Gencev himself has kindly told us that it is better than 90 dB. The low damping factor, typical of the monotriodes, forces to connect the VA 350 to gentle loudspeakers like my Mantra Sound Daiko, that are more efficient and have a more exigent module than the Stat Audio of Roberto “The Rock” Rocchi, considering the more suitable 4 Ohms manufacturing setting-out. With the Stat, characterized by a resistive module of 8 Ohms, the impression given is of an increased sound volume.


As stated by the designer, inside standard flying leads and ribbon cables connect spaced circuit boards. I have no objections about the manufacturing quality and the choice of the components. I had personally expected RCA connectors not directly soldered on a board, which is, in my opinion, rather cheap, but I am not a technician and the debate among the technicians is still open.

A Czech manufacturer supplies the transformers, in compliance with the specs. I want to specify, however, that also at the highest volume the amp is noiseless in the room, thanks to the transformers, and on the loudspeakers, thanks to the project. The switching on gives the typical “bump” on the woofers, due to the tension peak in switching on/off and to the consequent loading/unloading of the huge capacitors. Each adjustment-treat screw, nut or component is marked with red paint to signal a possible manumission.


The kit comprises an English brochure, an Allen key and the remote control, this last one sober but solid. There isn’t any power cable, which is yet to be completed for the IEC socket.



The tubes implemented in the amps are KR Audio‘s own. By hand, glass blowing, one by one. Nobody knows them better. Nobody makes any amps “around” the tubes with such perseverance. Their manufacturing quality is clearly perceptible at the listening. The sensation is like meeting the confidence and the aplomb of a well-off country gentleman, of a landowner from many generations. What tubes! What sound!

We are talking about an integrated amplifier. We are dealing with a planetary economic crisis. The object is expensive, very expensive. Nevertheless, you are going to spend lots of money in searching the best preamp and the perfect cables between pre and power amp, aren’t you? Obviously, the subject is always relevant even if the recreational part of the hi-end is lost. I think, this is extremely topical, though.



The tubes implemented in the amps are KR Audio‘s own. Unfortunately, this is a weakness if you want to buy their devices. They are quite perfect, unique and expensive. If you buy a KR Audio amp, you are, for better or for worse, tied to KR Audio. Most of all with this gear, which employs tubes that are unique in the world. You have just to know it. And enjoy a unique sound in the world, without compromising your savings with the more high-priced Kronzilla amps, whose single tube costs like an entire hi-fi system.

If you want to take advance from the KR Audio manufacturing quality and design, consider also the possibility of changing the tubes - an audiophile game that is allowed and very amusing. You can turn to the VA340 twin amp or to the VA300 Antares: two devices that employ the 300B, available in many productions, quality and brands, from the new old stock to the brand new item.


Who knows?

Many hardliner manufacturers of tube amplifiers will stick up their nose looking at the internal layout of this apparatus. “What?” they could say, “After having made all the efforts to create power tubes that are unique, you pre-amplify them with solid state components? The debate is open. I have personally listened to completely solid state amps that are performing in an irritating way and completely tube state amps performing in a disappointing way. Of course, a hybrid amp lends itself to technical considerations. What counts, at the end, is the result, isn’t it? And here, there result is incontrovertible.


Metaphors and final summary

I can summarize my listening impression about this and others Kr Audio amps in two words: disarming naturalness. And in other three words: control without oppression. From the outset, the VA350 seems to say to the loudspeakers: “OK, now I’ll take over and you perform as I want”. But how is doing it, is typical of the high lineage tube amps, like the best Audio Note, for example. I am very sensitive to a musical reproduction that is fluid, natural and maybe a bit dumped down. Between a brand new solid state amp like Vitus Audio and an old and obsolete Quicksilver, I would sonically prefer the second, ever. Who knows some hi-fi history can see that I am doing an extreme. But, finding these features in a non-euphonic or corny amp thrills me.

The VA350 performs like a SET: with immediacy, fluidity, sound integrity, plasticity and with that sound mold typical of the best tube products, which give back the sound in a way that cannot be renounced if you know how to listen to it. A clarification: when I say “sound mold” I do not mean something gummy or stolidly palpable. I mean that beautiful feeling of perfect amalgam that exists whit all the required ingredients, when they stay well together and are “well mixed”.

In a word, the VA350 performs as you would expect from a very good amp, not only a tube amp.

The strength points are its tube, its simplicity and clearness of design, its “well-chosen” tube power supply that exalts and doesn’t mortify it with alleged “designing simplifications”.

When put in the correct conditions of playing, I mean with loudspeakers that are equal to it and can interface with its operational range, the VA350 is a definitive amp.

As I suppose most of the KR Audio are.

Bravo, instant Spark, a small ReMusic award for a great achievement.



Tone color | frequency extension, capacity of a faithful reproduction of the instrument and of its harmonics

Complete, articulated, full bodied also on the bass (it is not a transistor) and with a slight softness on the screeching sounds together with a minimum of roll-off on the top high.

Dynamics | micro (detail) and macro (absolute), extension and velocity of the transients

Serene, modulated, realistic, optimum. It depends on the match with the loudspeakers: we are always talking of a SET. The attacks are very present, the releases too. The amp doesn’t go after the sound in a hyper-realistic way.

Image | setting, transparency, scene, soundstages, virtual stage, sense of presence, resolution

Wide, neutral, correct, balanced in giving back the stages, great presence-effect.

Tone | general setup of the device, if present or typical: for example warm, cold, colour changed, amber, bright, opaque…

Neutral, correct, without any colouring.

Emotion | capacity of emotional involvement, very depending on the match, an absolute anarchic and personal parameter

I felt my heart skip a beat from the first note. And my love continues.

Manufacture | Impeccable. Maybe we can confront on some details of the designing choices, but the outcome is incontrovertible. Who wins is always right.

Price/quality ratio | Absolutely expensive but unique in the world. This also because there are no amps with this tubes typology to make a comparison with.


Official technical specifications:

Power tubes: 2 x T100

Output power: 2 x 30WRMS (THD=3%)

Output impedance: 4.8Ohm

Frequency response: 20Hz -20KHz (-3dB)

Feedback: zero

Damping factor: Approx. 2.8

Preamplifier: solid-state with mechanical (reed) relays

Remote control: volume and channel selector

Inputs: 4 x line RCA (Cinch)

Input sensitivity: 0.75VRMS/47kOhm at 30W (for both channels)

Power requirements: 230/115VAC, 50/60Hz

Power consumption: 300VA

Operating temperature: 5C to 40C

Weight: approx. 37Kg

Dimensions including projecting parts and controls: approx. 53.5x30.5x41.5cm (WxHxD)

Official Italian dealer: to Extreme Audio website

Aldo Zaninello, tel. +39.0426.320318

Official Italian tubes distributor: to Tektron website

Official current price in Italy: 8,228.00 EUR

Associated equipment: to my system




Thank you, It's a great review. We are pleased with your understanding of the KR design concept (the KRT-100 is a superior 845 tube and used only for audio applications, while the 845 was originally projected for transmitting purposes) and hope that the average person will understand Riccardo's ideas for two channel stereo. KR will continue to carry his vision forward with the prayer that more people will find their way to our amplifiers through auditions or word of mouth.

Eunice Kron, KR Audio