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As stated earlier, the Japanese Teac/Esoteric enterprise -- founded in 1987 by Ohmachi-San to have been operational over two decades now -- is primarily famous for its digital source components. This stern focus has broadened of late and the integrated amplifier AI-10 -- the nomenclature's 10 mates it to the SA-10 -- is one example thereof. Sibling rivalry is active in the shared cosmetics, similar sticker and certain ingredients since the AI-10 doesn't just amplify but also keeps time via its internal master clock. This can be tapped from the BNC output to defeat the SA-10's own clock whereby the amp become master to the SA-10's slaved DAC.
Explaining its lack of macho heat sinks, the Esoteric AI-10 is a class-D amplifier, highly efficient to not consume redundant bias current or requiring much cooling. Pulse-width modulation is via Texas Instruments chip, switching by International Rectifier MOSFETs. The latter are tiny enough to elude detection by shortsighted publishers. Thankfully, Esoteric's German distributor was kind enough to put them under the microscope for us. Four of these dwarves per channel net maximally 150 watts into 8 ohms. Less shrunk is the toroidal power transformer which takes pride of place in the middle.
The master clock isn't the only added bonus. The AI-10 also sports an MM phono input which is far from common these days. A trick little switch 'round back converts this input into a standard line-level input for non-phono users. Excellent thinking. Two single-ended and one symmetrical analog input plus Toslink and coax digital i/ports for internal D/A conversion round out connectivity.


The sparse fascia houses a total of four push buttons and two rotary switches for volume control at right, input and menu selection at left. Menu access is via the setup button and controls various parameters such as input naming (for example, "CD" rather than "Line 1"); input sensitivity for the analog sockets; and choice of seven different master clock frequencies. To start the clock, press "word" or reach for the remote.


A word on word then: Does it make much of a difference? To put it diplomatically, you're allowed to use the CD player without it... Properly inclined, you might perceive an ever so subtle increase in image focus in the presence region and beyond but I didn't hear much else. The choice of digital filter setting seemed far more significant.
As concerns Esoteric's AI-10, I have to confess to initially treating it with little attention. I
was completely absorbed with playing digital musical chairs to assess the SA-10. Only in hindsight did it occur to me that the amp had to be quite transparent to so readily parlay differences in source components without exerting a powerful voice of its own. No shabby beginning, that.
Among the in-house amps I had for comparison -- from Myryad's pre/power combo or matching integrated to Dussun's V8i integrated and Bel Canto's Pre3/M300s threesome -- the one most price- and reputation-matched was the Accuphase E-212 integrated. This helped me identify one trait of the Esoteric AI-10 very quickly; its rather lean bass.
Cleaned up is perhaps more correct since it's clearly not thin per se and perfectly capable of heartily dry attacks. It's ultimate reach into the very basement that's not in the cards. With a clear and neutral
vocal band and treble -- 'neutral' implying neither unusual charm in the mids nor sweetness in the highs yet simultaneously no hardness either but high resolution and subjective speed -- the Esoteric AI-10 rendered the music very transparently and with great translucence.

'Translucent' applies as well to its soundstaging. Simultaneously occurring sounds were cleanly separated and layered particularly in the depth but also time domain where during fast bass runs, piano rushes, complex harp glissandi and such, nothing blurred. Clarity is as clarity does of course. One must fancy it. Some will call it analytical since it lacks that certain kissy lips fullness.

On closer inspection of both Accuphase and Esoteric integrated amps, I recognized two rather distinct sonic schools to make for quite the interesting juxtaposition. Two of my notorious test CDs -- OP8's Slush and Tord Gustavsen Trio's Changing Places -- would demonstrate these differences.
Clearly, the Accuphase E-212 was the fuller warmer amp. Should the Esoteric show a 1dB depression between 100 and 400Hz, the
Accuphase would counter with the equivalent rise. That's the subjective impression. The E-212 also produced the earthier, juicier bass. No wonder how one could be spontaneously smitten. The Esoteric bass meanwhile is more articulate, drier, more impulsive and faster, albeit not as massive. Asked which I prefer for well-recorded upright or advanced e-bass riffs (say Flea of the Peppers), I'd pick the Esoteric AI-10. Granted, this is personal taste. The Esoteric appeals to active listeners and simply resolves more detail. The Accuphase plays with more heart to be less dispassionate which isn't a fault either.

The Esoteric's treble is clearer not just because there's less mass down low. Hi-hat hits are more obvious and the ringing metal is more precisely rendered than over the Accuphase. At the very end of the Tord Gustavsen Trio's "ING", the hi-hat goes SCHschSCHschSCH, i.e. the fade oscillates in amplitude. The Accuphase makes this into sch_sch_sch, altogether more subdued and with drop-outs into utter silence. No doubt, the Esoteric is more detailed on high.
Likely due to this shift in tonal balance, both amplifiers also render dimensionality and localization cues differently. The Accuphase stages more broadly and not only presents music more expansively but nearly issues an invite to participate. This I related to strongly enough to be nearly a mite disappointed whenever I switched back to the Esoteric. The music seemed spontaneously more recessed, less expansive and gripping and it played reservedly from the base line between the speakers, albeit with impeccable technique. While not as laterally wide as the Accuphase, depth layering was superior and image focus
stronger. The Esoteric erected a showcase that was strictly ruled by organization, no whiff of fogginess in sight.
Did this make the Esoteric AI-10 an amp for analytical listener, more suitable for Jazz trios and classical albums? I nearly replied in the affirmative but things are never quite so simple. Ween's twofer Chocolate and Cheese contains a terrific e-guitar solo on "A Tear for Eddie" (incidentally one of those numbers which have me convinced that electric guitars are best served by analog source components. I've not yet met the CD player which would rival vinyl's tonality here.) In the second part, the guitar undergoes nicely dirty distortion. Here's my take on that: The Esoteric amp rendered the dirt more cleanly. This
enhanced insight into deliberate distortion was both a gas and rang more accurate. Because drums and beats were delivered with more damping too, the Esoteric AI-10 got my vote for the Ween disc.

Conclusion:
Esoteric's SA-10 (SA)CD player and AI-10 integrated amplifier represent the firm's entry-level offering. While €3.300 and 3.500 respectively are relative entry-level only, we're dealing with luxury brand Esoteric. It makes these components accessible to a broader audience and thus welcome and newsworthy.
To these ears, Esoteric's SA-10 sets very high standards for CD playback across the board and is committed to the neutral path of the born truth teller. This player is characterized by:
  • an agile, well defined bass which remains dry into the lowest reaches
  • a midband and treble which are perfectly linear, lucid and transparent and thus the essence of high fidelity
  • great dynamics both in the micro and macro domains. The Esoteric SA-10 is also a gifted player and blessed with rhythmically impulsive reflexes to convey the energy and life of the music
  • truly spectacular staging. Be it the strikingly transparent layering or -- even more so -- the absolutely impeccable image focus, more doesn't seem possible. Should it be, I'd call it too much already.
  • a minor weakness which curtails the ultimate decay of certain instruments. Alas, this depends on the choice of music and is valid only for the "narrow" setting of the digital filter. A simply button push to "wide" and this apparent minor liability turns asset because...
  • ...the shallower filter produces enhanced warmth and longer fades. This particularly benefits piano music to transform piano notes into piano runs. What you give up is a degree of image lock and staging transparency. This program-specific adaptability is a very useful feature.



Esoteric's integrated amplifier AI-10 exhibits the same design genetics and is committed to the ideals of transparency and accuracy:

  • Bass is athletically lean but nimble and impulsive. This benefits an exceedingly clear and informative midrange and the treble is rendered transparent and clear but with a careful brush
  • Bass runs are well damped, dry, properly articulated and full of swagger yet without sacrificing composure.
  • The AI-10 builds up the stage from the base line to afford the listener a clear view on the imaginary action.
  • Stage width is good, depth excellent and separation high.
  • The Esoteric AI-10 has good timing and rhythm to be clearly organized during rapidly lined up sounds. When called for, transients are hard and sudden and assumptions of restraint get a wakeup call whenever Power Rock is cued up. I'd be surprised if involuntary toe tapping wasn't the result then...
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