Tubes for the input stage, solid state for the output. The best of both worlds?

Take Michael Elliott's conceptual brief for his Aria Audio Ltd. WT100LS XL 100wpc hybrid power amplifier. It points at a rarely attempted interracial marriage of tubes' timbral "rightness" -- hence the WT Whole Tone moniker -- with the reliability, control and load-impedance invariance of transistors inside a single amplifier.

Any music lover familiar with the respective strengths and weaknesses of the thermionic versus silicon equation is liable, on paper at least, to instantly embrace such a hybrid architecture as the cat's meow. Throw in cost-no-object designer parts as does today's review XL version. A prefab mystique now rears its head. It promises precious fabulosity because it appeals to our well-groomed audiophile concepts: The slam, grip, linear can-do attitude of solid state with the sweeter, more dimensional magic of tubes. The latter are used in the amp's voltage stage to exploit their advantages, the transistors in the current stage where they shine with negligible output impedance and thus a high damping factor.

Like any properly indoctrinated audiophile, I was predestined to fall in love. Add that I had recently conducted an interview with Michael Elliott. I was now even more inclined, via the automatic sympathies from any kind of contact that exceeds bare formalities, to really look forward to this encounter, towing certain "I'm sure that" a priori conclusions in the shadows of consciousness.

To do a credible reviewing job, I had to of course annihilate this peculiar predisposition. Park it anywhere but in the listening room. I also had to prevent undue overcompensation. A reviewer friend, when reviewing components by makers he personally knows, dons a double-tough stern judge armour. To which a manufacturer who presently finds himself in such a scenario reacted nervously "don't do me any special favors, Your Honor, just use the same law for all of us sinners."

All this by way of sketching out how a reviewer should attend to his mental equilibrium before an assignment. Listening with our heads skewed by expectations or alliances is dangerous. This business is subjective enough to not cloud the issue any further. Some cerebral dry cleaning is in order - a good brainwashing in other words. Killing off some particularly busy brain cells with a 5-minute blood-pressure blasting headstand, I crawled to my listening seat properly decapitated. In the dark space of an empty mind, I groped for the remote control. I pressed the right button by mistake. Voila!

Behind bars

Actually, I played the amp for 1.5 weeks as nonstop as living logistics allowed before taking notes and letting the amp out of my self-imposed prison of background duty.


The first serious mode CD cued up was Vicente Amigo's Poeta, a Japanese import of a Flamenco Guitar Concerto with Symphony Orchestra and authentic Flamenco singers.

The recording quality on this Sony Records release is stupendous, the music's caloric value triple chocolate. The intricate juxtaposition of poetry recitals against ocean surf, flamenco guitar wizardry by a master musician whom many connoisseurs believe to be Paco de Lucia's unofficial successor, the full symphony orchestra of Cordoba under the able baton of conductor/orchestrator Leo Brouwer, the incisive Flamenco percussion of Tino di Geraldo and Luis Dulzaides and the bloodcurdling vocals of Jose Parra all combine into a broadly stretched canvas of dynamics, timbres and complex image localization that will challenge the finest amplifier.

Instant asset

From the first words of Miguel Bosé's reading of Rafael Alberti's opening poetry, the redolent perfume of palpable tubular presence caressed the senses.

The saturated timbre of the solo oboe was pellucidly aglow, and so were the massed strings.

The soundstage obliterated the front wall and layered far into the distance as you expect of a symphony orchestra but not that many solid state amps.
Instances of acid?

However, I also noted a subtly reticent top-end that sublimated the bite from the trumpets and the metallic shimmer on the rapid guitar tremolos.

A nagging suspicion of "aquatic drag" then arose that filtered a sense of excitement, the energetic immediacy that's such a powerful and addictive part of the percussion and palmas interludes, of the singer's raspy wildness, of the massive syncopated orchestral attempts to keep up with the guitar and machine-gun fire cajon percussion.

Opposing notions

Envision observing an underwater kelp forest as you would from behind the 3-story glass wall of the Monterey aquarium. It's directly connected to the sea for that perpetual dance of surface motion. However, surrounded by the sheer mass of cubic tons of salty liquid, these surface waves translate into a gentle slow-motion ballet of the kelp, its swaying modulated and buffered by the water.

Now shift your gaze to a willow tree in an open field ravaged by strong winds. On irregular horizontal air currents, each supple branch and leaf string is violently rattling, their every spasm an immediate unedited reaction to the surrounding air turbulence.

Admittedly, these examples are deliberately heightened for dramatic effect. Still, for all its hypnotic beauty, the aquarium scene is positively tame compared to the raw fierceness of the willow hanging on for dear life. Going back to my resident Art Audio PX-25, the vexing sense of rhythmic restraint (aquatic drag) was instantly transcended - now the music displayed the crackling atmospheric tension that I've come to expect from this recording also via the Bel Canto Design eVo 200.4.

Speed as a function of communicativeness

It seems the Aria's valve-preceeded push-pull circuitry doesn't quite harness the obvious speed of my two reference amps. By speed I mean incisive rhythmic precision, transient attack with dangerous rather than bullnosed edges - a propulsive sense of directness that jumps at you, not in any sense of tonal but energetic forwardness, what I think of as projection or communicativeness and also tend to equate with single-stage single-ended circuits done right.

By undoing six hex screws with the provided key, I popped the Aria's hood and replaced the stock Sovtek 6SN7GTs for a pair of Army/Navy surplus Sylvania VT-231s Michael Elliott had included next to some RCA 5692s and Philips WGTAs. I was curious whether what I had just observed was more a function of the particular tubes or one of overall circuit flavor.

The latter, it turned out. In fact, the Sylvanias enhanced the voluptuous midrange bloom yet further but also appreciably shadowed the top end. It was like putting olive oil into water - swirling the fluids around in a glass, the oil on the surface dampens the water's motility and slows it down.

As you may know, I'm quite the tube lover. In the Art Audio marquee, I first stumbled upon "my kind" of tube circuitry - one that defies traditional tube preconceptions. I hear excellent dynamics with a lively, exceptionally fast delivery. It's a kind of adrenaline-enhanced effect coupled to a pristine sonic purity, the Jota more brash than the slightly more polished PX-25. With a different tonal flavor but equivalent immediacy, I hear the same thing in Bel Canto's eVo range, in the AUDIOPAX monoblocks, in various Goldmund amplifiers. It's the tremendous dynamic jump factor of the Avantgardes, the vitality of the ClearView cables, the resolution and energy of the Audio Magic Stealth.

But what speaks to you may be Spanish to me: Olé !

It's how I have tuned my system to reflect traits I value most: Listener bias meets system synergy. Inserting an amplifier like today's pale silver/gold Aria gem into this recipe is bound to wreck havoc unless it so happened to wear the same colors and dovetail neatly into the vacancy of its resident predecessor. This is a dilemma. While I can tell you -- exactly --what the insertion accomplished, I'm not in an equally strong position to determine how the newcomer's respective traits could be shifted or tuned to alleviate or soften the present criticism - which, to keep perspective, might be a criticism only from my chair. To you, it may be nothing more than an interesting observation. One that distracts from other performance characteristics far more important to you - such as ...

(Before you convert initial impressions into baseline conclusions ,wait until the last page of this review - things will take a rather surprising turn!)

Grandeur and macro-dynamics

A litmus test for these qualities are large-scale symphonic works. I had just the right programme to enjoy profound substance and audiophile effects. For dynamic envelope, endless crescendoesque scaling and massed strings beauty that should enchant like lunar rays dancing on wafting gossamer - the Adagio of Prokofiev's 5th with Neeme Järvi directing the Scottish National Orchestra [Chandos 8450].

For grace (or lack thereof) under extreme duress, the last two minutes of the concluding Allegro giocoso, a most challenging bacchanal of brass roaring like bucks in heat, massive kettle drums interfering with complex syncopations of large orchestral sections, piccolos at ear-clipping intensity, and unexpected momentary retreats into orchestral whispers.

I needed to settle, out of the four pairs supplied, on one tube for the remainder of the audition. I had already written off the Sylvania VT-231 as the sauce Alfredo doom of a cholesterol-critical heart patient. Sumptuously midrangey but also thick and ponderous - fat coagulating in the veins and choking life force.

The Sovteks buckled under Prokofiev's friendly Russian fire. Though possibly exhibiting the most extended treble of the four, they turned steely and bright under heavy attack. They also couldn't equal the RCAs and Philips' for their preternatural deep silence and suave smoothness under less strenuous conditions.