Class D Audio SDS-470C

Original Owner.  I have owned them all (look at my Audiogon record and status, I think I'm the first on the site :)  Anyway, I own three, just scaling down to two stereo's so keeping the other 2.
The Class D Audio SDS-470C is a stereo power amplifier offering a potent 300 watts per channel into 8 ohm loads and twice that into 4 ohms. Read that again and be reminded that that precious few power amplifiers can manage this feat and those cost much much more. All this in a trim form factor that operates without producing significant heat, noise or fuss. How can it be?  

It's a class D amp! That alone will send many audiophiles running - and it should not. Class D amplifiers have been around for quite some time now and a significant number of good quality examples have appeared. The SDS-470C is made by Class D Audio, a relatively new small manufacturer offering a variety of power amplifiers available fully assembled, as complete kits and as discrete modules and components, all at very attractive price points. The company appears to have had limited exposure in the audio community and their relatively simple website certainly lacks any glossy audiophile trappings or wild claims. Communications with the proprietor are uncomplicated and very informative. The products are produced right here in the USA. 

The top-of-the-line SDS series is a half bridge self oscillating design based on International Rectifier output devices and backed by beefy linear power supplies. Facillities on the amplifier are basic - two red pilot lights on the front panel, a small rocker power switch on the side of the chassis, balanced (XLR) and single-ended inputs with selector toggles, volume pots and an IEC power socket in the rear. The build quality and appearance are reminicent of more expensive components. The steel casework has reasonable heft and the silk-screened front panel is attractive in an austere fashion. Not overbuilt, just well engineered. The electronic components are of high quality and the assembly appears to be first-rate. 

So how does the SDS-470C perform? The sound is very effortless, a trait often associated with powerful amplifiers. The noise floor is very low and results in a "black" background that preserves musical detail. Part of this certainly results from the inclusion of volume controls. Amplifier gain can be set to match the preamplifier optimizing system noise performance. There is very little tonal coloration. Midrange and high frequency performance is comparable to high quality conventional class A/B amplifiers and bass is taugnt and controlled. Other have described Class D Audio amplifiers as having a "tube-like" sound, and if that means grain-free and transparent then the SDS-470C certainly shares that quality. Imaging and soundstage reproduction are limited only by the source material, loudspeakers and listening room. These characteristics seem independent of the loudspeaker driven, unlike some other class D designs.  

In th final analysis, the Class D Audio SDS-470C provides excellent sound and blistering power in a relatively compact, cool running, and cost effective package. Highly recommended.