Bob Barret - Home Theater Review - Red Dragon Audio S500 Review

"Good things come in small packages." While that idiom may hold true for some things, it certainly hasn't been the conventional wisdom among audiophiles when considering the quality of amplifiers. The bigger and heavier the amp, the better, right? If lifting an amplifier doesn't cause your lower back to cry out, it can't be any good, can it?
Enter today's digital amplifier technology. For the past 10 years, Red Dragon Audio has been designing, building, and marketing digital amplifiers at realistic prices to audio and home theater enthusiasts in the U.S. and abroad, all from Salt Lake City, Utah. Until the opportunity came up to review the new Red Dragon Audio S500 stereo amplifier ($1,999), I hadn't actually listened to any of the company's products.
Sure, I had heard of Red Dragon and had even walked by its demo room at a couple of audio shows, but I never took the opportunity to stop in for a listen. There are always more products than time at a show. However, opportunity was on my side at T.H.E. SHOW Newport earlier this year, where Red Dragon was demoing the new S500 stereo amplifier. I made a point to stop by this time and get an audition. That brief listen piqued my interest. I liked what I heard (or rather, what I didn't) and looked forward to a more lengthy evaluation of the S500 in my own system. While talking with Ryan Tew, engineer and founder of Red Dragon Audio, about shipment details of a review sample, he asked if I might want two S500 amplifiers so that I could also audition them in BTL (bridge-tied load) bridged mono mode. I said yes and was shipped two units shortly thereafter.
Red Dragon utilizes a stock Pascal S-Pro2 amplifier module but adds a proprietary input buffer stage. Pascal A/S (Ltd.) may be unfamiliar to many audio enthusiasts. The company is headquartered in Copenhagen and best known for producing OEM amplifier modules for the Pro PA loudspeaker industry. While using a stock amplifier module helps Red Dragon to keep costs reasonable, this particular amplifier module has some unique features and was specifically designed for the audiophile market. Taking Class D technology a step beyond the more common ICEpower modules originally developed by B&O and found in many current digital amplifier designs, the S-Pro2 amplifier module incorporates Pascal's patented UMAC Class D technology. The S-Pro2 is said to be the world's only Class D amplifier without an HF (high frequency) damping network. This means it provides full power bandwidth to 20 kHz. As mentioned earlier, the S-Pro2 can be operated in either stereo mode or BTL bridged mono mode. That's a pretty unique feature for a digital amplifier at this price point. The S500 amplifier is rated at 2 x 250 watts at eight ohms (2 x 500 watts at four ohms) in single-ended mode or 1 x 1,000 watts at eight/four ohms in bridged mono mode. The S500 also has a maximum current output of 30 amps. This means that the S500 has a lot of power headroom and should be able to drive even difficult loudspeaker loads.
All of this power is packed into a 12-pound aluminum chassis with a form factor of just 16 inches by 7 inches by 3 inches. The minimalist industrial design of the S500 is available in either a brushed silver or anodized black finish, the latter being the finish of the review samples sent to me. Both the company name and dragon logo are engraved on the thick aluminum front panel, and the logo glows red when the unit is powered on.
While the increasing number of channels found in AV receivers in recent years has made the inclusion of digital amplifiers a practical necessity, the acceptance of their use in both mono and stereo designs has been slower to gain acceptance among the traditional audiophile community. These days however, there are several examples of digital amplifier products from respected high-end companies including Jeff Rowland, Gato Audio, and Classé. How do they sound? As Jerry Del Colliano so aptly pointed out in his recent review of the Classé Sigma AMP5 Class D five-channel amplifier, the old clichés that Class D amps sound clinical, lifeless and lack real bass aren't necessarily true anymore. Does that hold true for the Red Dragon S500 amp, as well? Well, that's what I intended to find out.
The Hookup
The back panel of the S500 is clearly labeled, making hookup a straightforward task. I first integrated a single S500 amplifier into my reference system using Wireworld Silver Eclipse 7 balanced interconnects and speaker cables to connect the amp to my reference Classé preamp and Aerial Acoustics floorstanding speakers. Connecting the speaker cable spade terminations to the amp's binding posts was an exercise in patience, given the tight space between connections and the stiffness of the speaker cables. Either having a little more real estate between connectors or banana terminations instead of spades would have made the job much easier. I also connected the 12-volt DC trigger output of my preamp to the trigger input of the S500 with the included cable to enable remote power on/off of the amplifier.
A couple of other adjustments were necessary before powering up the amp. There is a switch on the right side of the back panel to select between the RCA and XLR inputs. There is also a push-button switch on the back panel's left side to select between stereo and mono operation. This push button is recessed to prevent accidental engagement.
Over a two-month period, I listened to a wide variety of source material with a single S500 in stereo mode. Then I added the second S500 amplifier into the system, resetting the operation of the amps to bridged mono mode. Again, I listened to a lot of the same source material for another couple of months, but this time with a dedicated amp for each channel, effectively doubling the power output to each four-ohm Aerial Acoustic loudspeaker to a staggering 1,000 watts.