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This review first appeared in the January 2009 issue of hi-end hifi magazine High Fidelity of Poland. You can also read this review of the Art Audio Conductor & Diavolo in its original Polish version. We publish its English translation in a mutual syndication arrangement with publisher Wojciech Pacula. As is customary for our own reviews, the writer's signature at review's end shows an e-mail address should you have questions or wish to send feedback. All images contained in this review are the property of High Fidelity. - Ed.

Reviewer: Wojciech Pacula
Review system: Go here
Review components retails: 21.000 zł for Conductor with remote; 21.500 zł for Diavolo (EH 6922, EH 12BH7, TJ 274 and mesh-plate 300B); 1.500 zł additional for integrated Diavolo (adds volume control and three line-level inputs; 27 000 zł for reference NOS version; 1 500 zł for balanced input
During last year's Polish Audio Show, I talked to Art Audio owner Tom Willis who also functions as the company's technical director. Quiet and reserved, with a clear vision of what he wants and strives for, he does not enforce his ideas on anyone. The full interview will appear in Audio but I want to call upon its part about technology, to show the ideas behind his products.


Wojciech Pacuła: Do you think there are any new technologies ...
Tom Willis: ... just out there? (laughs)


WP: I thought more of what we already know, valuable technologies which would be able to replace those we have used since the beginning. Or will we rework the old ones over and over again?
TW: (thinks long) In my opinion, anything worthwhile in audio has been invented long ago.


WP: But those technologies and projects we talk about were presented by somebody for the first time...
TW: Yes, but those are things that turned out to be extremely long-lived and are hard to replace with something else. We can juggle with those and try to improve them. This is like with a meal - we as a company are cooks, taking ready-made partial products and adding spice to taste. We search for a certain sound and for 20 years now our company simply polishes what was our goal from the very beginning: more music, more melody, more information. The secret is not in chasing novelties but in the realization of proven ideas to convey the musicians' ideas in the best possible way.


WP: And for you the way of accomplishing that is with electron tubes?
TW: Absolutely! In my opinion, this is the only technology that allows us to not only communicate how the sound looks like but also what it carries - music.


WP: Your most expensive products utilize direct-heated 300B triodes - do you have a favorite supplier?
TW: If budget allows, there is only one tube and I've tried everything you can get your hands on - the Western Electric 300B. This is the tube for which the output transformers of the Diavolo were wired. You see, I must deal with many variables when designing an amplifier. But one of the things I can rely on are those tubes.

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And now everything is clear. We have already tested their Quintet amplifier but for the first time I now had the opportunity to listen to an Art Audio amplifier with a 300B in the output stage. The Diavolo is the result of Tom Willis' ideas. Because this is a power amplifier, I received the companion Conductor preamplifier as well which incorporates a headphone amplifier. The Diavolo is a SET with 300Bs and ECC88 and 12BH7A input and driver tubes and can be ordered with many different valves. Stock, we get the small-signal glass from Electro-Harmonix, the 300Bs as 'mesh plates' from the renowned Chinese maker TJ plus their 274B rectifiers. The latter are so big, they resemble a 300B from the outside. The distributor made sure the test would be versatile so he sent along additional tubes: Mullard GZ34 rectifiers, Philips E88CC SQ and RCA 12BH7A. He also arranged for the loan of Western Electric 300B (current production Westrex Corp) and Telefunken GZ34. After evaluating the various tubes, I settled on listening to the amplifier in the following configuration: WE 300B, Philips E88CC SQ, RCA 12BH7A, Mullard GZ34.


Sound
Changing from my reference Luxman M-800A to the Diavolo brought about a change of the sonic gestalt. I will begin by describing what degraded as this might be important to certain readers. With the Diavolo, worse by far was the bass. Because it extends far lower than for example the JAG 300B, the low power shortcomings were more apparent too. Forget about the definition or coherence offered by the solid state amp. You must be careful in picking the loudspeakers and their placement. With ill-advised choices, more bass will also incur more resonances. This won't be a big deal but taking into account other sound elements that operate at a very high level, it would be a pity not to provide this amplifier with the best possible operation conditions. Further, instrumental definition in space isn't as good as over my Luxman which is exceptional regardless of technology. The Diavolo trails it by half a step in how instrumental outlines are defined and focused in space.


Although the bass leaves no room for interpretation -- it is what it is and no different -- how the soundstage is defined and perceived can be interpreted differently because the Diavolo is a 10-watt tube amplifier. Here this amplifier is way ahead of any solid-state amplifier in terms of timbre and showing interactions between the instruments. This pursued the general direction set for me by the Reimyo PAT-777. The naturalness, ease and a kind of spontaneous joy whereby the Diavolo presents instruments is overwhelming. Quite transparent, a tad bright but incredibly clean loudspeakers like my Harpia Acoustics Dobermann suddenly had planar-speaker coherence from the mid-bass through the upper treble. Silky precision (I cannot improve upon this coincidentia oppositorum) showed natural timbres, reverb and harmony. Bettered only by the Reimyo, the vibraphone from the Modern Jazz Quartet's Pyramid disc sounded incredible. It had vibrant attacks and full, full saturation, admittedly a repetition but it describes the flavor well. Similarly surprising were the dynamics on drums and percussion, double bass and piano. Besides timbre, dynamic shading of every detail is the forté of this power amplifier. But unlike with the Luxman, this isn't imposed mercilessly during compressed portions or entire discs. While dynamic verisimilitude is phenomenal to not obscure anything, it does not outright expose the errors.