Soaring Audio SLC-A300 Amplifier


Soaring with the SLC-A300

Michael Wright

 May 2004


A new contender emerges

I was surprised to receive an email from our copy editor, Dave Thomas, with an offer to review an amplifier from Soaring Audio in light of the fact that he knew more about them than I did. I knew Dave had been in their room at the CES and had liked what he heard, but he didn’t say much else about the experience. I, on the other hand, was not familiar with this new company and concluded it would be a real nice learning experience and proceeded to look Soaring Audio up on the web. Sure enough, there they were and a phone call ensued. I had the pleasure of speaking with Dr. Bill Avery, the “Professor” part of the Soaring Audio triumvirate. The other two parts of the braintrust are Jan Coyle, the “Inventor”, and Daniel Kolbet, the “Golden Ears” of the operation. Dr. Avery is a very engaging man that seems passionate not only for his amplifier, but for music in general. After a couple of phone calls, and some assurance from me that his amplifier would be in the very best of hands, the Soaring Audio SLC-A300 arrived on my doorstep.

First, groundwork, then we Soar
Removing the amplifier from its box was a little awkward at first because it has a deceptively small footprint and considerable weight to it (38 lbs). If you don’t lift it out of the box just right, that weight will sneak up on you. Plus you’ll have to deal with some heat sinks that do have a little bit of an edge to them.

The SLC-A300 is tastefully done and has very good build quality. The owner’s manual, while not big, is full of helpful hints and good information that all lead to an enjoyable, worry free experience with the amplifier. The top and bottom covers, though somewhat thin, are made of .090” thick steel. “These amps are strong enough to allow for stacking three SLC-A300s on top of one another,” says Dr. Avery. I’m sure this adds to the amplifiers ability to stay cool under load. You should make sure you give it enough room to breathe (the owner’s manual says at least 3 inches for the top and sides). Common sense dictates not sticking anything through the top of the amp or putting it in an enclosed case. Looking down into the amplifier through the top cover you can see the power transformer, power supply capacitors and all of the amp’s inner workings. Everything appears to be neatly laid out and the construction and parts all seem to be first class. Moving on to the rear of the amp, there is the power cord connector, a pair of input connectors and some very nice Cardas speaker posts. 

Moving to the front of the amplifier is where it began to get interesting. There are three knobs on the front panel aside from the on/off switch. Next to the power switch, which is on the right, is a master volume control that allows you to go straight into the amplifier from your source. You simply control the output of the amplifier with this control and do not need a preamp. The other two knobs (one for each channel) are on the left and control what Soaring Audio calls a “Signal Loss Compensator” (SLC) circuit. According to Soaring Audio the SLC provides:

• Acoustic Restoration: smoothes 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 “smoothes 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 level. 

There is a lot to be said about the SLC circuit but for brevity sake I’ll just touch upon how to read the LEDs and how it relates to the sound you’ll hear. Each knob has two pairs of LEDs (a red pair and a green pair) that indicate whether you have enough signal coming in or if you’re overdriving the amplifier. Suffice it to say, you don’t want any of the red LEDs to come on. This indicates that you have reached the point where you will start to overdrive the amp and cause clipping. You’ll need to back off on the SLC control for that channel until you no longer see any red LEDs. When operating properly, only the green LEDs should light up when music is playing. Prospective buyers can read more about it on Soaring Audio’s website or contact them directly for a thorough, in-depth explanation; you’ll find these folks to be very knowledgeable and a delight to chat with.

All the connections were nice and solid. I did quite a bit of cable swapping while using this amplifier and it never misbehaved. The connections were always tight and I never had any incidents of hum or turn-on pops. The amplifier was always quiet when it was on.

Getting the caveats out of the way

Please, be mindful of the level of SLC enhancement you use. I know there is a lot to consider between the output on your preamp (if you choose to use one with this amplifier), the SLC level, and the output level control of the amplifier. It takes a little bit to get used to but if you put in the effort, you will be rewarded by the sound you get from this little gem. I’m almost certain that anyone who has a sonic issue with this amp will find that it is the result of not setting the levels correctly. I only had the red LED come on for me once. That was when I went from using my own preamp to using the line level control of the amplifier. Other than that, I never got the red LEDs to come on. The green LEDs went from just coming on with the loud transients of the music to flashing on and off continuously.

The sound of an amplifier Soaring

As I mentioned before, one of the features of this amplifier is that you don’t have to use a preamp with it unless you choose to. You can come out of your source straight into the amplifier and control the volume at the output control on the front of the amp. I do have to add that I did the majority of my listening through the preamps I had on hand because I felt they sounded better that way. Going straight into the amp from the source works just fine and sounds okay too. I felt I had a greater sense of openness and high frequency extension coming into the amp with my preamps. Your conclusions may be different. I have to confess to being pleasantly surprised by the performance of this amplifier. There is just no way I thought it would be able to drive my Martin-Logan Quests to satisfying levels with program material that ranged from rock and r&b to classical and movie soundtracks. I was never able to make this amp clip, or sound hard or bright. Do keep in mind that I don’t listen to music crazy loud, but the wife has been known to come downstairs and shoot me that “where is your mind?” look. The amp always sounded neutral and musical. By that I mean it never sounded bright or etched or overly detailed and only sounded on the warm side of neutral when I used a tubed preamp with it. I can’t stress the importance of making sure you set the SLC levels appropriately and by that I don’t mean set them on each piece of music you play. You will reach a point where you feel you’re at a good enough level to see the benefits of the control and not overdrive the amp. The controls are very consistent and that has to help. I used the A300 while I did my review of the Sonic Euphoria passive line stage and the music was generally very detailed, dynamic, open and scads of musical information from all over the stage. The transient response was very good and the bass was always tight. When I switched over to the Thor preamp, the music became slightly more alive with a wider, deeper stage and the bass seemed fuller, slightly more natural. This amp does not throw an image quite as wide or deep as the Conrad-Johnson MF2500A no matter which preamp I used. What it did do was give a high degree of focus to the musical performers on the stage.

Soaring Dynamically

I made one major change to my system that really took the A300’s performance to another level. I inserted Dynamic Design’s White interconnect on the source and between the preamp and the A300. Speaker cables were the Dynamic Design Silver with their Bass Bi-wire cables running to alternately, the Martin-Logans or the Von Schweikert 4.5s. The music gained a new scale of musicality, detail and high and low frequency extension. And the change wasn’t subtle. This cable really worked well with the A300. The performances and voices began to soar, as they probably would say at Soaring Audio. This was especially so when listening to The Dead Can Dance’s Toward the Within [4AD] CD. Lisa Gerrard’s voice is just mesmerizing, both beautiful and haunting at the same time throughout the entire performance. I also especially enjoyed Brendan Perry’s vocal work on Oman.

The A300 captured the verve and the passion of the vastly underrated Lew Soloff and George Young playing Round Midnight on the Manhattan Jazz Quintet’s My Funny Valentine CD [ProJazz]. Another memorable moment came when listening to the Tin Hat Trio’s CD The Rodeo Eroded. I could practically close my eyes and swear Willie Nelson was in my room while he sang the wonderfulWillow Weep For Me. Moving on to classical, I heard a nice layering affect from Bela Bartok’s Dance Suite from the Mercury Living Presence offering featuring Antal Dorati conducting the Philharmonic Hungarica Orchestra. Moving a little more up tempo, I listened to the title track from Grover Washington Jr’s Mister Magic [Kudu]. This is an urban jazz classic where Grover and Eric Gale lay down the easily recognizable melody that feels as good as nice pair of slippers at the end of a hard day. Pretty much the same can be said of Herbie Hancock’s Chameleon from his classic album Head Hunter. With Herbie laying down synthesized bass tracks to start things off and Benny Maupin following that up on the tenor sax, you can easily follow Herbie’s transition to the Fender Rhodes electric piano as the track takes a change of pace midway through the performance. 


On Soaring Audio’s website and some of their literature they refer to the SLC-A300 as a “Home Theatre Stereo Amplifier”. I know, as a regular audio guy, there is a propensity not to take something with “Home Theatre” in the name seriously as an audio product. But despite that peculiar piece of nomenclature, the SLC-A300 performs like a pure audiophile-grade amplifier. I don’t have a surround sound system and could not test the video sound playback capabilities of the amp. It did perform splendidly as a two-channel main amplifier and I’ve used it for evaluating cables and other audio equipment. Look, there are several really good amplifiers in the $3000-$4000 price range such as the Cary V12, Bryston 4BST, and CJ MF2500A among a slew of others. But you can easily add the SLC-A300 to that list.

Soaring Audio also has an 800 watt monoblock version of this amplifier coming out without the SLC circuitry called the A800. Based on my experience with the A300, I can’t wait to give the A800 a listen. Stay tuned. As for the A300 … Highly Recommended!

Output Power: 100 watts per channel at 8 ohms RMS
150 watts per channel at 4 ohms RMS
Frequency response: -3dB from 0.1Hz to 300kHz at 1 watt
Hum: Hum: typically over 120dB below peak output (Over a 100 times quieter than the noise floor of a CD.) 
Input Level: 1-4 volts RMS
Load Impedance: Rated for 3 to 16 ohms in Stereo mode
Watt Usage: 6 plugged in; 60 on idling; 500 at full power
Dimensions: 17 X 16 X 4
Weight: 38 lbs; Shipping weight 48 lbs.
Serial Number: 30043
Price: $3,400


Soaring Audio, Inc.
2900 Fantasy Lane
Sparks, NV 89436
Tel: (866) 640-SOAR (Toll Free USA & Canada) 
(775) 425-8000
Fax:(775) 425-3000

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