Click on Photo Above to See a Larger
● Power: 100 Watts RMS x 2 into 8
Ohms; 150 Watts x 2 into 4 Ohms;
Class A/B; 60 Watts Consumption
● MFR: 0.1 Hz - 300 kHz - 3 dB
● Noise: - 120 dB
● Weight: 38 Pounds
Options: Balanced Input, 240 VAC,
● MSRP: $3400 USA
Soaring Audio, Inc.
It was the last day of CES 2004. To say I was feeling burned out is a
gross understatement. To compound the stress of “so many exhibitors, so
little time,” the fabled future spouse was in tow, and hardly in a state
of bliss. So when we encountered “The Professor” walking back and forth in
the Alexis Park courtyard handing out flyers posing the question “BEST
SOUND OF THE SHOW?” and claiming that a number of listeners had proclaimed
as much, our inner cynic geared itself up for a jolly good time. How could
this upstart company dare claim to have better sound than that encountered
in the Edge/Epiphany, Joule/Joseph/Elrod and Talon rooms (to name just
three fine sounding rooms of many)?
Upon entering the Soaring Audio Suite, we encountered a setup dominated
by huge Magnepan 3.6s. The sound, at least from where I was seated, was so
sonically oversized and out of proportion that I could neither make sense
of it nor fairly evaluate the amp. A visit to the second room, accompanied
by “The Professor’s” wife and sales manager Daniel Kolbet gave my inner
cynic a huge charge when designer Professor Dr. Bill Avery’s name was
invoked with a titled reverence usually reserved for religious leaders.
It goes without saying that we were told that “The Professor” had
carefully chosen parts (as though no one else did the same) in order to
achieve an extraordinary level of sound. Unfortunately, such an
extraordinary experience escaped us both in a cramped space filled with
not two but at least five surround speakers. What was whispered into my
ear when future spouse and I were seated alone shall not be repeated.
Nonetheless, I strive to be fair. Hence I asked for a review sample. As I
was soon to discover chez Serinus, the Soaring Audio SLC-A300 sounds far
better than it did in the cramped CES demo spaces. In fact, it has a hell
of a lot going for it.
The amp comes supplied with one of the most user-friendly, delightfully
designed manuals I have yet encountered. Each point, commented upon by the
“Professor,” then receives extra commentary from the “Golden Ears” of
Daniel Kolbet. Further “Bean Counter” commentary explains why certain
design choices were made regardless of cost. Color printing and heavy
stock paper add to the visual impact.
No regular reader of Secrets reviews is under the illusion that my
technical expertise amounts to a hill of beans compared to that of other
veteran members of the Secrets staff. My strong point is music, which I
revere, perform, and experience live and recorded as often as possible. I
therefore encourage you to examine technical discussion at the Soaring
Audio website, from which I quote verbatim.
The most unique aspect of the amp’s design is SA’s patented SLC analog
SLC is claimed to provide:
“Acoustic Restoration: smooths [sic] out digital grit. Digital to Analog
converters send out a voltage that is read from a CD or DVD at 44,100 or
48,000 voltage samples each second. The SLC ‘smooths [sic] across’ these
discontinuities and gives the impression of having a higher sampling rate.
In surround sound it brings out details that are lost because of the
compression in 5.1 formats.
“Enhanced imaging: left and right enhanced outputs combine to form a solid
phantom center channel that is wide and deep.
“Dynamic detailing: increases the perceptual dynamic range, at any output
“In video images, the apparent sharpness of a picture can be increased by
employing a technique called edge enhancement. The impression to the human
eye is that the focus has been sharpened and more detail is visible. In an
analogous way, by adding a tiny emphasis to certain details in the
waveform, the impression to the human ear is that the details of the sound
stage are more clearly perceived.”
The SLC-A300 can be fed a signal directly from a CD player or processor.
If the signal is high enough, no preamp is needed.
The front of the amp offers an on/off button, a light that shows when the
amp is on, and a master volume control knob toward the right side.
In addition, there are two enhancement level control knobs on the left
front, one for each channel. These are adjusted with the help of four LEDs
Green Lights, Red Lights
The input pair of LEDs on the left reflects the level of the RCA inputs.
The input level is adjusted by adjusting the output level of the preamp or
The output pair of LEDs on the right reflects the amount of signal
enhancement. The amp’s output level is adjusted by turning the two
enhancement level control knobs.
Input Green indicates presence of normal signal level for optimum
enhancement. If the Green Input light does not come on, the input signal
can be adjusted by balancing the preamp or source’s output level with the
amp’s input level. This necessitates both adjusting the source output
level and also turning the amp’s master volume levels and corresponding
enhancement volume level knobs up and down. It may take a few minutes to
get a feel for, but it’s easy to do.
Input Red indicates that the maximum level (5 volts RMS) for which the
input was designed has been reached. Clipping occurs just above this
point. To avoid clipping, the input green light should flash without ever
activating the red. It may take awhile to get there. The big challenge is
getting it right with wide dynamic recordings, such as Reference
Recordings’ Rachmaninoff Symphonic Dances. I personally found it
challenging to get the green lights to come on in soft passages without
the red lights beaming away in loud passages. Better to have the green
lights come on occasionally, I shortly discovered.
Output Green indicates good enhancement to the signal.
Output red should normally not come on, since it indicates that the
maximum design level of enhancement has been reached and clipping is
Welcome to the SLC-300A light show. At any moment, four green lights and
occasional no-no red lights may flash away as music plays. Yes, Virginia,
there is a Santa Claus.
The lights are small and not overly bright, thank goodness. Nonetheless,
the visual experience does seem reminiscent of those mass-market receivers
of old, complete with all kinds of illuminated bells and whistles that
make everything appear far more technically complex than necessary. Such
flashing light features were dropped when designers discovered that they
fascinated many men (not this one) but drove women away in droves.
Of course, the difference between the flashing lights of the ‘80s and
those on the Soaring Audio is that the latter are necessary for optimal
adjustment. They are intended, not to impress, but to enhance.
The rear panel consists of an IEC connector for a removable power cable,
one set of single-ended audio inputs, and one set of speaker wire outputs
that accommodates spade lug terminations. High quality Cardas speaker
connectors are employed. There are also major size heat sinks, preferable
to the noise of a fan.
Initial Impressions and System Transformation
Soon after connecting the amp for the first time, I called Bill Avery to
further understand how to best evaluate the signal enhancement feature. He
suggested I first listen flat, with the Theta DAC/preamp’s volume turned
up, the amp’s left SLC knobs turned off, and the amp’s right master volume
control turned up as far as possible.
This produced no sound whatsoever. I found that I had to add enough signal
enhancement to achieve listenable levels. I therefore kept preamp and main
volume levels very high, turning SLC controls up only as far as necessary
to achieve desired volume level. No green lights flashed as a result.
Shortly after my first listening session, we moved to our new home. Sound
chez Bellecci-Serinus is a whole different experience.
Chez Serinus’ spongy top-level apartment wooden floor has been replaced by
a ground-level, well-supported wooden floor. The result is much firmer
bass, with bass pitch far more well-defined.
The ceilings are now 9’2” high rather than 8.5’. Speakers are farther from
the back wall and farther apart, with the listening room depth close to 24
feet. I sit much closer than that, but there is ample room behind me. Even
more important, an additional 12-15 feet of open space extends on either
side of the speakers. My Talon Khorus X speakers finally have room to
As for my power, there is an equally major difference. Instead of
compromised, ancient 14- and 12-gauge wiring running the length of three
floors and two fuse boxes, I’m listening via brand new 10-gauge wiring on
a dedicated 30-amp line. In place of a grounding wire to a cold water
pipe, I’ve got an actual grounding rod driven into the earth. As before,
wiring leads directly into a PS Audio Ultimate Outlet which is connected
to the P600 Power Plant by means of an Elrod EPS-3 Signature power cable.
Though I still have some fine room tuning to do, the sound of my reference
system in this new space, complete with the Theta Generation VIII DAC/preamp,
is eminently musical, frequently approaching the magical. It’s far more
live, satisfying and boundless than before.
With and Without SLC
My reactions to the amp without SLC were lukewarm. Auditioning the stereo
layer of Michael Tilson Thomas’ new multi-layer surround sound SACD of
Mahler’s Fourth Symphony (SFS Media) was a case in point. I found the
strings a little wiry, lacking the smoothness I heard during the
symphony’s actual live performance or on other high-resolution SFS
recordings. Horns blared a bit, and cymbals sounded clattery. I also found
the midrange lacking in richness. On the other hand, bass seemed even more
impressive than with my Jadis Defy 7. Such perceptions were reinforced as
I listened to a number of the discs chosen for audition.
Then I fully engaged SLC enhancement. This was accomplished by first
turning the master volume all the way off, turning the SLC knobs up to 12
o’clock and beyond, and finally adjusting the balance between all volume
controls on Theta and Soaring Audio. It took awhile to get it right. But
once I did, I only had to make minimal readjustment for other recordings.
Engaging SLC radically changed the sound. In Soaring Audio terminology, I
had created a “Phantom Center Channel” Though I heard no more phantom
center channel than with any other excellent stereo amp I’ve auditioned,
SLC definitely fleshed out the sound. The midrange seemed far fuller, the
highs smoother and easy on the ear if at times a bit damped.
When my extended listening had concluded, there was no question in my mind
that taking advantage of SLC, regardless of the fact that it enhances
signal by slightly adding reverb and boosting certain frequencies,
provides a very satisfying listening experience.
My usual caveat applies here. My reference amp, the Jadis Defy 7, would
cost at least three times more than the Soaring Audio SLC-A300 by today’s
standards. It is also a tube product, with all the advantages and
disadvantages thereof. For those who have not seen the superb dialogue
between Harry Pearson, Robert Harley, Jonathan Valin and Paul Seydor on
the sonic differences between tube and solid state, I highly recommend it.
My experience confirms theirs.
Knowing that Secrets readers love different kinds of music, I chose seven
recordings total. Two were full symphonic spectaculars, Reference
Recordings’ "Rachmaninoff Symphonic Dances" and MTT’s "Mahler Symphony No. 4".
Others included Hilary Hahn’s "Brahms’ Violin Concerto"; Benny Carter and
Rosa Passos’ great bossa nova disc on Chesky; an early disc from jazz
vocalist Diana Kraal; Terry Evans singing the blues on a recording I’ve
mentioned more times than there are stars in the sky, and soprano Karina
Gauvin singing Canteloube’s "Songs of the Auvergne" with chamber
The first thing that struck me about the A300 with SLC engaged was the
fullness of its sound. This is a powerful amp. The bass is deeply
extended, the midrange quite full. I especially checked out the final
double bass conclusion to Mahler’s Symphony No. 4, the drums in the second
song on the Auvergne disc, and Ron Carter’s bass. In all cases, I heard
more pronounced bass from the SLC-A300 than from the Jadis. A definite
At the same time, I missed the beauty of highs and continuity of tone I
hear from the Jadis. Despite claims of an extremely low noise floor, I
experienced less transparency from the Soaring Audio than from the Jadis.
The “blacker black” we audiophiles long for was not quite there. The
mesmerizing liquid transparency I hear on the Audioquest/JVC-XRCD "Terry
Evans Puttin it Down" was also absent. Highs did not ideally shimmer and
glisten, distinct three-dimensional layers of sound and textures did not
David commented that on the Songs of the Auvergne, Karina Gauvin’s voice
seemed more removed than he was used to hearing. “There doesn’t seem to be
a foreground; she seems almost behind the instruments.” I heard this as a
lack of depth between voice and instruments made more apparent by less
transparency, clarity, and high extension than I hear with the Jadis.
I also failed to hear the same realistic quality to the triangle that I
usually hear on Rachmaninoff’s Symphonic Dances. It seemed flatter, with
less resonance and decay. I also heard less reverb around the voices of
Diana Kraal, Rosa Passos, and Terry Evans. David commented that while
engaging SLC made the sound more full, it also made Terry Evans sound more
removed and filtered than before. “More transistor-like” became his most
commonly uttered commentary on the difference between the two amps.
But remember. Please remember. I am not only talking about the differences
between tube and solid state, but also about amps in entirely different
price categories. My sonic recollections of solid state amps in the
Soaring Audio’s price range leads me to conclude that it is quite an
excellent performer. It certainly has a better tonal balance and a far
fuller fuller midrange than the upgraded McCormack DNAs I’ve heard in my
own system and at two other friends’ homes.
On the Bench (JEJ)
1 kHz and 5 volts output into 8 Ohms measured a little higher than we
usually see, but this could be a result of low negative feedback or other
was very low, using 1 kHz and 1.5 kHz sine wave input signals. THD was
relatively high, comparatively speaking.
With 5 kHz and 6 kHz input signals, again, IMD was low,
but THD was high, comparatively.
kHz, THD was approaching 1% at 5 volts output into 8 Ohms.
Frequency response was 0.5 dB from 20 Hz to 96 kHz, which is
For those drawn to the solid bass and full presentation of solid-state
products, the Soaring Audio SLC-A300 is highly competitive with other amps
in its price range. Some consider it amongst the best products released in
the past year. With its unique SLC engaged, this amp will bring much
pleasure to listeners. Most definitely deserving of an audition.
- Jason Victor Serinus -
Digital Front End
Sony 707ES transport modified by Alexander Peychev of APL Hi-Fi
Theta Gen VIII DAC/Preamp
Jadis Defy 7 Mk IV modified with a Siltech silver harness
Talon Khorus X speakers (with latest modifications and Bybee filters that
render its response even across the spectrum and greatly improve the bass)
Nordost Valhalla single-ended interconnects and balanced digital
Nordost Valhalla bi-wired speaker cable
Acoustic Zen Silver Reference II balanced interconnects
Powercables: Elrod EPS-1, 2, and 3 and EPS-2 and -3 Signature on main
chain plus Harmonic Tech, Nordost, and AudioPrism SuperNatural S2
PS Audio P600 Power Plant power synthesizer with MultiWave II
PS Audio Ultimate Outlet; PS Audio Power Ports
Michael Green Deluxe Ultrarack, Basic Racks and room treatment,
Michael Green Audiopoints, Ganymede supports. Marigo supports and Black
Diamond Racing Cones
Bedini Quadra Beam Ultraclarifier
Marigo Stealth Mat for CDs
Ayre demagnetizing/break-in disc
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