Esoteric AI-10 Integrated
The Oxford English Dictionary defines esoteric as that
which is "intended for or understood by only a small number of people with a
specialized knowledge." Hmmm, I thought: Could there be a more
appropriate title for a high-end audio company? The very name suggests exclusivity --
something out of reach or beyond the means of most.
Esoteric is to Japan-based TEAC as Lexus is to Toyota -- i.e.,
an upscale brand of a parent company -- and they have a broad range of products, including
CD players, transports, DACs, preamps, power amps, even speakers. Often, Esoteric products
are expensive, and most, if not all, of them are unique in one way or another. The subject
of this review, the AI-10, is not simply an integrated amplifier. With an onboard
analog-to-digital and digital-to-analog converters, as well as a master-clock sync
generator for use with Esoterics other digital products, the AI-10 occupies a
product class all its own.
But unlike many Esoteric products, the AI-10 costs only
$5000 USD -- by high-end as well as Esoteric standards, a moderate price that puts its
squarely in the company of other topflight integrated amplifiers, such as the Stello Ai500 and the Bryston B100
SST, both of which Ive reviewed. When I received my review sample of the AI-10,
I quickly hooked it up to hear what it could do.
Weighing just under 32 pounds and measuring 17 3/8"W x
5 7/8"H x 15 1/16"D, the Esoteric AI-10 sits on three sturdy isolation feet and
comes clad in a beautiful brushed-aluminum case. The top panel is an impressive 5mm thick,
while the sides are only slightly thinner at 4mm. The small display, with blue text, looks
very sharp, especially in a dark room, where the user can adjust the brightness or turn it
off altogether. The front panel exudes simplicity and consists of just four buttons
(Power, Setup, Word, Muting) and two rotary dials (Input, Volume).
The AI-10s amplifier section, an efficient switching
design with a 205VA toroidal transformer in combination with MOSFET transistors, is said
to produce 110Wpc into 8 ohms or 150Wpc into 4 ohms -- which, if true, is enough power for
What distinguishes the AI-10 from other integrated amps is
that it also serves as a master-clock sync generator. Master-clock sync allows the
retiming of the DAC to the transport device of a compatible CD player (such as
Esoterics own SA-10 or UZ-1) capable of inputting a sync signal (word clock). The
frequency of the word-sync signal comes factory-set at 100kHz, but can be changed by
pressing the Word button on the front panel (or on the remote control) to 44.1, 48, 88.2,
96, 176.4, or 192kHz. Once the CD players clock is synchronized with the
AI-10s master clock, Esoteric claims, improvements can be heard in soundstaging,
transparency, and imaging. Unfortunately, I didnt have a compatible CD player that
could input a word clock, and therefore wasnt able to take advantage of this
On the AI-10s rear panel are one optical and one
coaxial digital input for a DAC section that accepts resolutions of up to 24-bit/192kHz.
This takes the incoming PCM digital bitstream and generates pulse-width modulation (PWM)
signals using a Texas Instruments TAS5076 chip. These signals are used to directly drive
the power-amplifier stage. Therefore, the AI-10 can drive speakers from a CD transport
without the use of an external DAC. In addition, the AI-10 converts all incoming
analog signals to digital before they reach the amplification stage. This is done by an
AKM 5385B, a 24-bit/192kHz, two-channel A/D converter chip. Once signal conversion is
complete, it undergoes the same PWM processing described above.
These unique features had me concerned about the net effect
on the sound of all this processing. Id never encountered these features before, so
I contacted the folks at Esoteric to find out why theyd used this approach. It turns
out there were several reasons. One is that, during the process of generating the PWM
signal, fluctuations in the power supply will not influence the power-amplification stage.
Furthermore, this circuitry doesnt introduce noisy feedback, while allowing Esoteric
to make use of its clock technology. Finally, the engineers had already learned a great
deal about PWM while developing their AZ-1 integrated. They found they could achieve
excellent sonic results using PWM processors and amplifiers, which prompted them to use it
in the AI-10. They employed hand-selected components and left the final tuning of the
sound to Esoterics president, Motoaki Ohmachi.
Also on the rear panel are one pair of balanced XLR inputs
and three pairs of line-level RCA inputs. The last RCA input can be switched between two
settings: Line makes it a standard line-level input, while Line/Phono turns on the phono
stage, which supports moving-magnet or high-output moving-coil cartridges. After passing
through an analog phono equalizer, the signal undergoes the same A/D conversion as all
other analog inputs before sending the PCM signal on to the PWM architecture. It seems
that more and more companies are including phono stages in their integrated amplifiers; as
a vinyl enthusiast, I welcome this trend.
The Setup button on the front panel allows the user to
perform several functions. One is to match the gains of all line-level inputs so that the
outputs of all connected components are at about the same volume. This is particularly
useful when trying to evaluate different components. Setup also allows the user to change
the name of the inputs shown on the display, as well as to skip those inputs not in use.
For example, if a CD player is connected to Line 2, the input can be programmed to read
"CD" rather than "Line 2." Not only does this customize the AI-10
based on the listeners system, the ability to remove unused inputs makes it faster
to scroll through the list of connected components.
Another nice feature of the AI-10 is something called
S-VOL, for "Starting Volume." This allows the user to preset a volume to which
the unit will automatically return every time its powered up. Most of us have at one
time or another received a good scare when we turn on our stereo, after having forgotten
to turn down the volume at the end of the last listening session. Of course, if jumping
out of your skin isnt a concern, S-VOL can be turned off; in that case, the AI-10
automatically returns to the last volume set.
On the rear is a small panel labeled "Reserve."
This can be removed when an optional hardware upgrade, i.Link, is installed. The i.Link
terminal is an interface that sends digital audio from CDs, DVDs, and SACDs between the
AI-10 and the connected external device, allowing multiple external devices to be
connected in a daisy chain. For example, three AI-10s can be connected to a single
i.Link-equipped SACD player to produce surround sound from six channels.
The AI-10s full-function remote control can also be
used to operate an Esoteric CD or DVD player. Not only is the remote backlit for use in
poor light, its backside is wrapped in leather -- it wont scratch any surface on
which its set. The AI-10s speaker terminals, manufactured by WBT, accept
spades, banana plugs, or bare wire.
Clearly, the people at Esoteric havent sacrificed
convenience in designing the AI-10. This product is well thought out, and unique in its
category. All that remained was to listen to it.
System and sound
An NAD C542 CD player was connected to the AI-10 using
Kimber Kable Tonik interconnects. A Thorens TD-160HD turntable with modified Rega RB250
tonearm, on which was mounted a Dynavector DV10x5 high-output moving-coil cartridge,
performed analog duties. This communicated with the Esoteric via AMX Optimum RCA
interconnects. PSB Platinum M2 speakers comprised the last link of this audio chain. All
electronics were plugged into an ExactPower EP15A power conditioner/regenerator.
As a writer for the SoundStage! Network, Ive reviewed
a fair number of integrated amplifiers. While some have performed extremely well, only a
few have been able to raise the bar a little higher. What set those components apart was
their level of refinement, mostly owing to the fact that they had little sound of their
own. Combined with their ability to sound effortless and bring a genuine sense of ease to
the music, these integrated amps epitomize "high-end" sound. It was in this
category that the AI-10 found itself.
First, like the Stello Ai500 I recently reviewed,
Esoterics AI-10 was pretty much dead quiet in use. Basically, this means that it had
an uncanny ability to retrieve low-level details from good recordings. Not only did this
let me hear deep into recordings, it also tended to capture performances in a way that
made them seem more pure, and closer to the original.
This was particularly true when I listened to "Be Your
Husband," sung a cappella by the late Jeff Buckley on his marvelous Live at Sin-é
(CD, Columbia/Legacy C2K 89202). Through the AI-10, the small acoustic space of this New
York City coffeehouse was captured with near-startling realism -- I could hear the quiet
chatter of the audience and the clinking of glasses with astonishing clarity. I never
heard Buckley perform during his lifetime, but Live at Sin-é gives an amazing
glimpse of what it must have been like to have been present when these performances were
recorded. With an ultraclean integrated such as the Esoteric, it wasnt difficult to
imagine myself sitting in that audience.
In his upper registers, Buckley sounded open and clear, the
AI-10 readily exposing his slightest shifts in tone. The midrange was delivered with power
and lucidity, as Buckley projected the amazing confidence and certainty of an artist
honing his craft. The AI-10 sailed through each song with ease, stepping out of the way
without adding to the music its own sonic imprint. There was no coloration at all in its
sound, not even a subtle shading. So long as the source material was well recorded to
begin with, the AI-10 allowed that quality to be heard.
Then I cued up Neil Youngs Live at Massey Hall
1971 (CD, Reprise CDW 43327). The Esoterics incredible transparency continued to
clearly reveal cues about the recording venue, much as it had with Live at Sin-é.
However, unlike the intimate coffeehouse in which Jeff Buckley had performed, Young had
given his concert in Torontos Massey Hall, a much larger space. This was evident
from the sounds of coughing, laughter, and applause that came from an audience clearly
sitting farther away from Young than Buckleys audience had been from him. Still, it
was possible to imagine sitting on stage with Young and looking out into the crowd. His
acoustic guitar and piano sounded as natural as Ive ever heard them, the strings
resonating with crispness and purity against a black background. I could almost hear a pin
drop on the stage.
My listening sessions with the AI-10 took place during the
Christmas season, and I found myself putting on some festive favorites. Among these was
Loreena McKennitts To Drive the Cold Winter Away (CD, Quinlan Road QRCD102).
The desolation evoked by "Snow" is due in part to the fact that McKennitt sings
the piece in the large, empty space of Glenstal Abbey, in Ireland -- a perfect aural
metaphor for the mood evoked by the lyrics, a 19th-century poem by Archibald Lampman. The
Esoterics exceptional ability to capture Glenstal Abbeys ambience was second
to none, and a major reason I prefer this version of "Snow" to the one on
McKennitts more recent A Midwinter Nights Dream (CD, Quinlan Road
QRCD112). That 2008 release was recorded in a studio; despite the reverb added to this
version of "Snow," it doesnt come close to equaling the expansiveness of
the earlier one.
However, A Midwinter Nights Dream is still
very well recorded, a fact that was immediately evident through the Esoteric. The AI-10
was able to create a tangible, uncluttered, three-dimensional soundstage across which the
musicians were placed with sharp outlines and a good sense of space around them.
Percussion was taut and quick, while the sounds of the assorted stringed instruments were
equally fast and precise, conveying wonderful transient snap and speed.
Though I would never describe the AI-10 as analytical, it
definitely wasnt warm or euphonic. Highs were extended and quick, while the midrange
was detailed, open, and clear. Although its sound was full and pleasing, it also had
complete control at the frequency extremes, where its poise and precision were extremely
|The AI-10s Phono Stage
The Esoteric AI-10 comes equipped with a built-in phono stage
compatible with moving-magnet or high-output moving-coil cartridges. As my turntable is
equipped with a Dynavector 10X5 high-output MC, I spent considerable time enjoying this
Perhaps unsurprisingly, the AI-10s phono stage had
much in common with the sonic character of the rest of the component. By this I mean that
it was very quiet (at least within the limits of analog playback) and sounded incredibly
clear. Music emerged from as black a background as Ive heard from my turntable,
allowing low-level information and subtle musical details to surface. With particularly
quiet-sounding LPs such as the Beastie Boys Ill Communication (LP, Capitol
94232 1), the casual listener could be forgiven for thinking that he or she was listening
to a CD. The bass on this record was fast and tight, with characteristic analog warmth but
without the bloat or fuzziness of less poised integrateds. It still amazes me how
intoxicating vinyl can be; after listening to some LPs through the AI-10, I was feeling
I moved on to Portisheads Third (LP,
Island/Universal LC 00407). The AI-10s phono stage did a superb job of conveying the
immense, sometimes haunting feeling of space in which Beth Gibbons finds herself singing
these trip-pop tunes. The music expanded from wall to wall of my room, extending well
beyond the boundaries of the speakers and shrouding me in the dark murk that characterizes
Portisheads sound. Through the AI-10 the music flowed effortlessly, immersing me
even more as I enthusiastically turned up the volume.
If you own a turntable and want to get the most from your
LPs, the Esoteric makes a good argument for itself with a very-high-quality phono stage
thats part of the basic package. If youve got a compatible cartridge, this
could be the factor that tips the scales in favor of your owning an AI-10.
. . . Philip Beaudette
The AI-10 could easily fill my room with controlled and
articulate low frequencies, but never added warmth or weight. This made it sound a touch
drier than integrated amplifiers that dont exercise its degree of control down low,
and first became apparent when I listened to "Suntoucher," from Groove
Armadas Goodbye Country (Hello Nightclub) (CD, Zomba 9230492). The bass on
this track is incredibly deep; while the AI-10 was more than up to the task of playing
deep (at least within the limits of my bookshelf speakers), it didnt sound too
weighty or fat. Much like its performance higher in the audioband, the AI-10 was clean as
a whistle down low. If you want your room filled with rich, warm bass, this Esoteric
probably wont be to your liking. However, if you value controlled bass that
isnt exaggerated, and displays the discipline of a Zen monk, you need to hear the
AI-10. It consistently impressed me with its speed and tightness, and it had no trouble
getting my foot tapping as I was swept up in the rhythm of the music.
AI-10 vs. B100 SST
I compared the Esoteric AI-10 with my reference integrated
amplifier, Brystons B100 SST ($2995). Although the B100 is less expensive in its
base configuration than the AI-10, the addition of optional onboard D/A conversion, MM
phono stage, and remote control brings the Brystons total cost to $4795, making it
an almost direct competitor for the AI-10 ($5000).
Both integrateds are full-featured, with numerous input
options, onboard digital conversion, phono stages, and remote control. However, the
Esoteric pulls ahead with its inclusion of a master-clock sync generator, i.Link hardware,
S-VOL, and its ability to let the user individually set and cancel each inputs gain.
In terms of rated power, it was almost a toss up (Bryston rates the B100 at 100Wpc into 8
ohms or 180Wpc into 4 ohms), and was never an issue at the volumes at which I listen to
music. One isnt likely to be chosen over the other on the sole basis of their power
As I listened to various discs and switched between these
two components, I became more certain of something I mentioned above: that about $5000 is
a point of diminishing returns for an integrated amplifier. Spending more mostly buys a
sound thats different, not one thats inherently superior.
Thats what I heard while comparing the AI-10 and
B100. Both performed at such a high level that I found it impossible to say that one was
clearly better. Rather, as is so often the case in subjective evaluations, the better of
these two integrateds will be that which more closely satisfies the listeners sonic
preferences. Playing "Going Nowhere," from Elliott Smiths New Moon
(CD, Kill Rock Stars KRS455), both the Esoteric and Bryston sounded exceptionally clean
and transparent, both placing Smiths voice front and center, as if he were sitting
in my room. In terms of his voice, I could hear very little difference between the amps.
Listening more closely to the sound of Smiths guitar, however, Id give
the slight edge to the Esoteric, which was able to reproduce the subtlest details as Smith
fingerpicked the tune, sliding his hand up and down the frets. Again, it was like being in
the room with him as he played. It wasnt that the B100 wasnt detailed, but
that the AI-10s ultra-tidy sound helped me be more aware of such details.
"Going Nowhere" also helped me discern
differences in the two integrateds bass reproduction. Through the AI-10, the
acoustic bass had ample weight and extension; with the B100, the instrument sounded fuller
and weightier in my room. I also noticed this with Groove Armadas
"Suntoucher": the Bryston was simply more powerful down low, making the Esoteric
sound leaner by comparison.
Until the Stello Ai500 arrived for review, it had been some
time since Id heard an integrated amplifier that I enjoyed as much as my own
reference, the Bryston B100 SST. With the arrival of the Esoteric AI-10, Ive found
another. The AI-10 came up in the reviewing queue almost immediately after Id sent
back the Ai500, so it seems the old adage is true: when it rains, it pours. Luckily for
me, getting rained on means being saturated with wonderful sound. Thats a shower I
dont mind taking.
. . . Philip Beaudette
|Esoteric AI-10 Integrated Amplifier-DAC
Price: $5000 USD.
Warranty: Three years parts and labor with warranty-card return (two years without).
7733 Telegraph Road
Montebello, CA 90640
Phone: (323) 726-0303