Stello DA100 Signature
Digital-to-Analog Converter and CDT100 Transport
by Tim Shea
||"One of the first
discs I played was Donald Fagans Morph the Cat (Reprise 49975), and via 24/192
upsampling, what was immediately apparent was how the sound decoupled itself from the speakers
and stretched from wall to wall. In comparison, when I switched back to the other modes the
sound became increasingly smaller and more localized between the speakers." Also,
"the little things like sibilants and bows scraping on strings seemed better integrated
when fully upsampled." "I kept coming back to 24/192 for pure listening
||The DA100 Signature
"sports a custom-designed sixth-order filter and asynchronous sampling-rate converter
using proprietary clock circuitry to address jitter, which is claimed to be extremely
low." It "will take a native digital input of up to 24 bits and 96kHz and upsample
to 24 bits and96kHz or 24 bits and 192kHz at the push of a button." The DAC and transport
share five inputs/outputs: "AES/EBU, optical (TosLink), USB, S/PDIF coaxial, and, most
notably for audiophiles, I2S."
||"And what of this
vaunted I2S connection? Well, Id like to tell you it took the experience to a
whole new level, but that was not the case.... I suspect that the I2S cable
provided was a little more polite-sounding than I would like in the context of my
system." "A more eccentric feature is that for the CDT100 to read each new
discs TOC information you need to press the Disc button, otherwise it will continue to
report the information from whatever disc was previously under the puck."
||"To me, the
inclusion of I2S indicates that April Music really cares about providing the best
sound possible along with high value."
Musicality. Now theres a word
thats overused in audiophile circles. Musicality is one of those things that most of
us seem to be able to hear and appreciate, but ask any number of people what it means and
youre likely to get as many definitions as people you ask. Why is that? I think the
simple answer is that musicality can mean different things to different people depending
on their individual preferences, biases, and past experiences with live and recorded
So why bring up musicality? Well, it's the word
that came to mind when I first heard the Stello DA100 Signature DAC and CDT100 transport
in my system. Also, after finally getting around to reading the Stello manuals, I found
that it played a prominent design role for these Stello 100-series components.
"Youll be amazed how digital sound can be transformed into something musically
seductive and emotionally satisfying," say the manuals.
Now, I suspect about a third of audiophiles will
read this and think it sounds very intriguing. Another third will have red flags going up,
sensing that such emphasis on musicality must mean adding something to the music
that isnt there to begin with, or subtracting something that is present. And then
theres the last third, who, like me, have a goodly dose of both reactions. Having
had the opportunity to review the excellent Stello DP200 preamp/DAC four years ago, I
wasnt too concerned because I found that unit to be quite refined and neutral in
character. Doug Schneider has also been very positive in his reviews of the various
iterations of the Stello DA220 DAC, and both units have earned Reviewers Choice
nods. But the DA100 Signature and CDT100 are part of April Musics entry-level series
of downsized components, so it remained to be seen if any necessary cost- or size-cutting
efforts affected their performance.
Background and description
For those of you who may be unfamiliar with the
company, April Music is based in Seoul, Korea and has been around for ten years. The DA100
Signature ($995 USD) and CDT100 ($895) are siblings to the S100 stereo amplifier and HP100
preamplifier/headphone amplifier as well as a non-Signature version of the DA100, all of
which are the same general size and weight. The DA100 Signature weighs a sturdy 8 pounds
and measures 8 3/8"W x 2 1/8"H x 11 1/2"D. In addition to its fully
discrete, class-A analog output stage and sizable, custom-made 25VA toroidal transformer,
the little DAC includes some unexpected tasty bits for its price class, such as WIMA
polypropylene capacitors, 1% tolerance metal-film resistors, beefy Cardas RCA connectors,
and Neutrik XLR connectors.
The DA100 Signature sports a custom-designed
sixth-order filter and asynchronous sampling-rate converter using proprietary clock
circuitry to address jitter, which is claimed to be extremely low. It has five inputs,
including AES/EBU, optical (TosLink), USB, S/PDIF coaxial, and, most notably for
audiophiles, I2S (more on this later). That last connection is one of the main
differentiators between the Signature and non-Signature versions of the DA100 (along with
many other DACs at several multiples of its cost). So, yes, feel free to use the DA100
Signature to upgrade the sound of your cable box, computer, and basically almost anything
with a digital output. (Note, however, that it does not support an ASIO driver for use
with a computer soundcard.) The rotary knob used to select among the inputs clicks into
place with a solid "thunk" that is fully consistent with the quality hinted at
in the design elements listed above. This thing is built.
That being said, I need to disclose that the
first unit I received started to malfunction shortly after arrival. April Music promptly
sent a replacement that worked perfectly but then insisted on sending another unit that
was tested at the factory. It also, not surprisingly, worked perfectly. The majority of
the review was conducted with the third sample.
So what does all this supposed quality and
engineering get you? Well, the DA100 Signature will take a native digital input -- up to
24 bits and 96kHz -- and upsample to 24 bits and 96kHz or 24 bits and 192kHz at the push
of a button. Bypassing upsampling altogether is also possible. Unfortunately switching can
only be done from the front of the unit (there is no remote), and although I understand
there are cost concerns at these price levels, it would have been nice to be able to
toggle through the three options with a remote to more easily detect performance
differences. But, hey, at least the option is there, which is more than many DACs can
boast. The signal-to-noise ratio is claimed to be 120dB along with a typical dynamic range
Anyone who has operated a CD or DVD player can
operate the CDT100 right out of the box -- with a couple exceptions. First, it is a
top-loading unit that demands you place a magnetic puck on top of the CD before playing
(there is also a top cover you can put on, but it is optional). A more eccentric feature
is that for the CDT100 to read each new discs TOC information, you need to press the
Disc button, otherwise it will continue to report the information from whatever disc was
previously under the puck.
Other than these little personality traits,
operationally the CDT100 was very easy to use and live with. The only standouts were the
display, which has a four-level brightness control and is big enough to see from across
the room, even with dirty contact lenses. Very nice. The negative counterpart is that
track access can be relatively slow, although not painfully so. I will say that
operationally I found the CDT100 to be just fine and much preferred to my Oppo DV-970HD
transport, with its woefully inadequate display and scan capabilities. Size and weight of
the unit are exactly equal to that of the DA100 Signature.
Now, about this I2S thing. For those
who are unfamiliar with this connection, it is widely held to be the best available for
digital transmission. Much the way a component video cable differs from and improves upon
a standard composite video cable -- by parsing the video signal into its individual
components -- an I2S cable carries the bit clock, word clock, master clock and
audio data on their own dedicated conductors rather than bunching them together as on a
more typical digital connection. One of the main advantages of this format is that the DAC
does not have to recover clock information from the data stream, thus avoiding a common
source of jitter. Jitter is a blurring of timing information within the digital signal and
can produce smearing and distortion that are audible and unpleasant. An additional benefit
of transmitting the digital signal this way is that the DAC doesnt have to use the
S/PDIF or AES/EBU transmit and receive circuitry that can also be a potential source of
jitter, so this is yet another case in audio where less is more.
The downside is that this type of connection is
more expensive to implement, and I was very surprised and impressed to see it on
components in the DA100's and CDT100's price class. In fact, off the top of my head, I
cant think of another DAC/transport combo near the sub-$2000 price range to offer
this connection. To me, the inclusion of I2S indicates that April Music really
cares about providing the best sound possible along with high value.
Sounds of April Music
There is certainly a lot of flexibility in terms
of tailoring the DA100 Signature's sound to your liking. As far as the upsampling goes,
the best analogy I can think of is, again, in video terms. On many HDTVs I see at
friends homes and in bars and restaurants, it looks like the sharpness control is
cranked up way too high, giving the perception of added detail but carrying with it some
unnatural noise. As you turn down the sharpness you lose some of that perceived detail,
but you also gain a smoother, more filmlike presentation that seems much more pleasing and
natural, at least to my eyes.
Loudspeakers Soliloquy 6.2.
Amplifier Bryston 2B-SST
C-Series and McCormack DNA 0.5 Rev. A.
Preamplifier Bryston BP 6 C-Series
and Marsh Sound Design MSD-P2000b.
Digital Oppo DV-970HD universal A/V
player (used as transport), Electronic Visionary Systems Millennium DAC 1
Interconnects Acoustic Zen Silver
Reference II and Stereovox Colibri-R.
Speaker cables Acoustic Zen Satori,
Apogee Wyde Eye and Stereovox XV2 coaxial cables.
The various upsampling modes in the DA100
Signature gave my ears the same exact treatment. Toggling from the bypass setting to the
24-bit/96kHz upsampling mode and ultimately to 24-bit/192kHz resulted in slightly less
perceived detail, air, and space but also imparted an increase in smoothness, continuity,
and naturalness. While the lower modes sounded quite good on their own, there was more
highlighted detail seemingly for its own sake, while the 24-bit/192kHz mode allowed the
detail to blend into a coherent overall performance. Although not quite as detailed, its
portrayal was consistently the most balanced and natural of the bunch, and dare I say the
one that would keep vinylphiles most interested.
One of the first discs I played was Donald
Fagans Morph the Cat (Reprise 49975), and via 24/192 upsampling, what was
immediately apparent was how the sound decoupled itself from the speakers and stretched
from wall to wall. In comparison, when I switched back to the other modes the sound became
increasingly smaller and more localized between the speakers. Despite the smoothing
effect, the trumpet in "The Great Pagoda of Funn" still sounded a little hard,
as it probably should with the mute in, but tonally there was more there compared to the
other modes. Bass was also deeper and richer, if a little less tight and quick.
I switched to something a little subtler,
Ushers demonstration CD Be There (Weichen Publishing House CO. LTD, no
catalog number), which contains some interesting tracks of varying styles. I try not to be
too subjective in reviews because its difficult for anyone whos not me to take
a whole lot from it, but on "Serenade," the fully upsampled cello was more
expressive and emotionally involving. And on "Wind Blowing Gently," I had a
significantly stronger feeling that the singer was singing right to me, a feeling that was
greatly diminished in the lower modes. I would also note that the little things like
sibilants and bows scraping on strings seemed better integrated when fully upsampled. I
dont know whether this was due to a slight softening of transient details or whether
the signal itself was achieving a more accurate and balanced form, but my guess would be a
combination of both. Regardless, it was there.
Back when I reviewed the Stello DP 200, I used Sera
Una Noche (M A Recordings M052A) to gauge the units ability to throw a
believable three-dimensional soundstage and came away feeling it was indeed a strength.
The DA100 Signature sounded very similar in this regard. But it was this disc that also
served to uncover something about the upsampling: As it was increased, the trail of reverb
information within the space became relatively shorter in duration and length. There was
still a very strong sense that this disc was recorded in a large space, which it was, but
it was more like you might expect to hear at a live concert rather than a detailed
recording of one. Was this editorializing for the sake of musicality, or were the
lower-rez modes artificially dialing up the sharpness control? To be honest, I enjoyed
both for this recording, but I kept coming back to 24/192 for pure listening enjoyment.
|More on the DA100 Signature and
A couple of years ago I called Stello
"the best-kept secret in high-end audio." I wrote that because not enough people
knew about this Korea-based company and its great product lineup. Thats starting to
change, particularly because Stello has been around for some time now. But I suspect that
theres still a long way to go, and products like the CDT100 and DA100 Signature will
help in this regard.
As a CD spinner, the CDT100 works well, but I have two nits
to pick. First, while some people like top-loading CD players and transports, I
dont. You usually have to put the component on the top of the equipment rack to gain
proper access to it, and when you put the disc in the player you have to secure it with a
supplied "puck" to hold it in place. This means more hassles than with a
front-loading player. Second, the CDT100 doesnt automatically read the table of
contents when you put a new disc in. You have to press Disc. If you dont, the CDT100
will actually remember the TOC from the disc before and play back according to that track
listing. I found that a little strange. On the other hand, the CDT100 only costs $895, so,
considering all the outputs and that its built so well, its easy to overlook
I have no complaints about the DA100 Signature, and when
the combo plays music (via I2S in my listening sessions), I was nothing but
thrilled with the result. The CDT100/DA100 Signature combo sounds refined and detailed,
and it can be compared against the best out there, whether its a one-piece player or
separates. The midband is very clear and well detailed, the highs sweet, and the bass
range articulate and highly controlled. Imaging is razor sharp, and the ability to project
depth, usually the result of high resolution, is superb.
Its been a long time since I reviewed the
DA220 with my Theta Data Basic transport (June 2004, to be exact), but if memory
serves me correctly this setup is better. So, at the combo's asking price, $1890, I have
nothing to complain about. Like the DA220, to better it, youd have to pay multiples
of the asking price, and even then you wouldnt be guaranteed that youd get
improvement, perhaps only something different.
On their own or together, the DA100 Signature and CDT100
are very good products that, like the original DA220, are benchmarks for value. You can
certainly spend more, but you wont necessarily get digital separates that are
better-sounding or have more features.
What about the DACs quirky little
companion, the CDT100 transport? Here the differences were tougher to discern, as
throughout the frequency realm I found the CDT100 to be perfectly balanced. Where it
really strutted its stuff -- and set itself apart -- was in creating a sense of
transparency and dimension within the soundstage. Voices became a little clearer and
spatial relationships easier to discern, especially front to back. Now, these required a
lot of switching back and forth to identify, and that balance may not seem like much for
your roughly 800 bucks, but the CDT100 certainly complemented and unleashed the inherent
abilities of its DAC brother. Whats more, I was able to hear the same differences
when using the CDT100 with my own DAC, so it was consistent and repeatable. If you care
about such things and youre currently using a budget transport, Id say the
CDT100 is well worth considering.
And what of this vaunted I2S
connection? Well, Id like to tell you it took the experience to a whole new level,
but that was not the case. There were some clear and significant advantages in terms of
individual instruments and voices coming across as more "of a piece" rather than
different sounds being combined into one. And there was more of an organic flow to the
music, but the problem was that the I2S cable supplied by April Music was
different in sonic character from the more revealing Stereovox XV2 coaxial cable I use as
a reference. So it was impossible to separate which improvements or shortcomings were due
to the cable and which to the format itself. I suspect that the I2S cable
provided was a little more polite-sounding than I would like in the context of my system,
and I think an I2S cable from Stereovox (if it existed) would have proven to be
very interesting. Given what I heard with this flawed comparison, I tend to think
there are some significant performance advantages to be had here, and I consider the
availability of the I2S connection at the Stello components' price point to be
a major bonus. I certainly would be intrigued enough to explore further.
How does April stack up to May or June?
Relative to my longtime reference, the Electronic
Visionary Systems Millennium DAC 1 ($650 when available) and Oppo DV-970HD universal A/V
player ($149 when available), the Stello units sounded more similar to than different from
my references when the DAC was in bypass mode. The EVS DAC 1 and Oppo player were
relatively more robust, up front, and dynamic, but the Stello products countered with more
refined highs and upper mids and a more dimensional presentation that unfolded behind the
speakers. On balance, it was kind of a toss-up, with the nod going to the Stello DAC given
my preferences. However, once the 24/192 option kicked in things were different. That
almost phasey imaging detached from the speakers and spread throughout the room was the
deal-maker that more than offset the slightly diminished sense of perceived detail.
As for the CDT100, it displayed superior
transparency that resulted in a better spatial rendering of images throughout the stage
compared to my Oppo DV-970HD. The fact that it costs more than five times as much as the
Oppo player is significant, but so are the build quality, audio-related features, and
performance advantages offered.
I could live with either of these two budget
DAC/transport combinations, and I'm happy I live with one of them. But if I had my pick,
it would be the Stello DAC and transport, especially with 24/192 upsampling engaged.
Overall, I found the Stello DA100 Signature to be
an extremely flexible DAC with a refined sonic character. Its gave me multiple ways to
experience and enjoy music. I always see people asking for a DAC that sounds more like
analog, or at least one that doesnt sound like digital. Especially with the DA100
Signature in 24/192 mode, I would heartily recommend giving this one a listen. The fact
that its built well and offers USB, AES/EBU, and I2S inputs along
with a couple different upsampling options, is merely icing on the cake, especially at its
asking price. The benefits wrought by the CDT100 were more subtle but still tangible and
meaningful if transparency and dimensional imaging are important, and to most audiophiles
they certainly are, no matter where they can get them. The fact that the CDT100 is the
perfect mate to a DAC as accomplished as its sibling is a big selling point, but I found
the benefits translated to my decade-old DAC as well.
There has been an explosion of digital processors
that promise to bring new levels of performance to cable boxes, computers, and music
servers. Given the high level of performance these Stello devices can deliver, its
almost sickening to think of them being wasted in an armoire feeding crappy computer
speakers or some mid-fi home-theater/audio combo rig. I have no doubt theyd improve
the sound in those applications, but given the level of performance and refinement I heard
in my system, doing this would be like using a Porsche to deliver the mail.
To those who have been looking for a digital
source that wont offend your analog senses or sap too much green from your vinyl
budget, you may find a viable option in the Stello DA100 Signature and CDT100 -- and even
some musicality from a digital source.
|Stello DA100 Signature Digital-to-Analog
Converter and CDT100 Transport
Prices: DA100 Signature, $995 USD; CDT100, $895.
Warranty: Two years parts and labor.
April Music, Inc.
894-18 Alpha Bldg, Bangbae-Dong
Seocho-Gu, Seoul 137-829 South Korea
Phone: 82 2 3446 5561
Fax: 82 2 3446 5564
May Audio Marketing
2150 Liberty Drive, Unit 7
Niagara Falls, NY 14304
Phone: (716) 283-4434, (800) 554-4517
Fax: (716) 283-6264
111 Zenway Boulevard, Unit 8
Woodbridge, Ontario L4H 3H9
Phone: (905) 265-8675, (800) 572-0205
Fax: (905) 265-8595