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With my Yamamoto A-09S and First Watt F4 and F5 in standby to take the comparative pulse, there was no guess work. For its price, the Sonata is one stupendous achievement. What it can really do requires a preamp to appreciate. But that, in my experience, is nearly universally true for 'passive integrateds', i.e. amplifier circuits with a preceding passive pot rather than a full-blown preamplifier stage. They sound better with the pot fully opened. And I wasn't the only one to think so. Which takes nothing whatever away from the Sonata integrated concept at 3000 euros.

First comments came from Vinnie Rossi who received his CES units before Hannes got his batch or I my loaner: "Hi Hannes, merry Christmas! The Sonata is fantastic sounding - but when I connected the Isabella with built-in DAC, holy shit! What an 'ear-gasm'! This is an incredible combo. Now I understand why you like it so much! As long as the customer does not need more than 30 watts per channel, this is going to be impossible to beat! You did a very nice job with the enclosure design and Sasa has the most impressive sounding EL34 amp design I have ever heard. I have always liked the EL34 sound but never heard it like this before..."

While it's indeed very fine sporting form to be this complimentary to a competitor, hard-nosed cynics could spot a bit of back-handed self promotion. The Isabella is after all Vinnie's own product. Not only is he correct though, it's not about the Isabella per se. Any good preamp can perform the impedance matching which makes the audible difference. Well, not just any in fact. The very best combo I could create was with Hegel's fantastic transistor P-10, a single-stage, zero-feedback, single-ended dual-differential design with merely a JFET (per phase) and one or two resistors (relay volume control) in the signal path. Because my reference amps are amps and not integrateds, I first ran the Sonata off the Thorens TEP 3800, the Hegel and my personal ModWright DM 36.5. With the Sonata's pot fully opened, I could thus compare on the fly and swap conveniently between the four amplifiers below.

This quickly determined that the TEP 3800/F5 and P-10/Sonata combos sat in the same tight inner circle of what I consider an ideal mix of resolution and tone color. The tube pre/transistor power duo held the edge in absolute resolution and transparency but surprisingly, the solid-state pre/valve power combo was close*. Those expecting the typical round-over softness (lesser diplomacy calls it fuzzy girth), i.e. the comfort sound we're used to from still affordable push/pull EL34 valve amps will be quite surprised. One can thicken the stew with a valve preamp if desired. This will compound THD interactions some for enhanced harmonic padding. But it will also step down separation and insight. The Sonata clearly does harvest from the EL34/6CA7 the 'bluesy' tone which makes it a favorite with guitar slingers. But it does so in a far more conservative than libertine fashion. This is presumably due to undisclosed winding and core composition trickery in those fully potted output transformers (the power tranny is potted as well).

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* Quick-witted readers will already have done the math to realize that in either case, the preamps were between 3 to 5 times the price of the amplifiers. Should you conclude that, in the bigger scheme, it's more expensive to make really good preamps than amplifiers (if the latter aren't asked to drive ridiculous loads), I'd heartily concur.
I also had a quartet of EI 'fat bottle' 6CA7s from my Eastern Electric M520 integrated to experiment with versus the Sonata's stock JJ EL34s

The fully optimized Sonata -- preceded by a transistor preamp that is -- has excellent non-excessive tone color, potent dynamic scaling, deep staging and on-the-string magnification power to separate out metal and wood components. Quite unexpected, its treble extension and ability to capture very minuscule decay sprays was very close to the F5. That transistor marvel does this trick on well-recorded piano tinkles the very best out of what my amplifier stable presently houses. Nelson Pass calls it tintinnabulation. It's that very rich, multi-hued ringing of bells which, like a halo, should surround undamped piano treble and triangles. And the Sonata's got it too, more so than my Japanese 300B SET.
On my ASI Tango R speakers with their ruler-flat <1kHz 6-ohm impedance and driven off its 4-ohm taps, the Sonata's bass was nearly as articulate and controlled as over the FirstWatt, which is to say it lacked the bloom or looseness lesser valve amps celebrate as a matter of misguided pride. WLM's own La Scala is a voluptuously tuned down-ported design to be bloomier by nature. I reduced its port diameter to the smallest option via the included compression-fitting discs. Presto, I got just the right mix of bass dryness and inner juiciness. The La Scala's minimalist crossover makes it ideal for tube amps by the way.
My first getting-to-know-her sessions arrived at the -- rather unexpected -- conclusion that minus a quite inconsiderable reduction of see-between-the-actors spaciousness one gets from premium transistors and the same fine loss in bass grippiness, the Sonata behaved rather transistorized. In matters of tone color and image density of course, she was a quintessentially valved vixen and as such, instantly recognizably from behind a curtain. If experienced auditioners were asked to guess on price with the curtain still drawn, they'd invariably overshoot because of the design's wholesale reduction of tube liabilities. As you spend more money, tube designs tend to get less overtly tub-ish just as the better solid-state designs begin to sound less obviously transistorized. Differences remain which, as above, can often be sublimated to near zero with a preamp of the opposite persuasion. Still, the obvious goal of most credible amp designer is to make output device identification by ear very difficult if not impossible. The means should become invisible to the end. All that is expected. It's common place and exactly as these things should be. What's not common place is to get there at the Sonata's asking price.


By way of context, a quick trip to our landlord's wine cellar was in order. We share it with him for (mostly audio boxes and their contents) storage. Anyway, this downstairs descent hauled up the M520 integrated from Hong Kong's Eastern Electric brand that was designed by the very gifted Alex Yeung. It offers 28 class A watts in pentode mode with adjustable NFB and is, to quote from my older review, "...tube-rectified with one 5AR4 per channel, preamplified with an EF86 followed by a 12AU7 phase splitter for the duet of EL34s, the nomenclature M520 referring to a famous historic Mullard circuit that was implemented by such brands as Leak, Eico and Audio Master." This A/B was the most even-handed real-world comparison I could put together and generated confirmations of my first impressions.