Photo: Hawk Audio

Class-D amplifiers are known for their superhigh efficiencies and precise, detailed sound, and much of their growing success can be credited to a single remarkable product: the Universal Class D (UcD) amplifier module designed by Bruno Putzeys of Hypex Electronics, in Groningen, the Netherlands.

It's used in high-end amps from Channel Islands Audio, Meridian, Kharma, MM Audio, and Exodus, and it's gotten raves from the audiophile press. But at prices in excess of US $1000 for a stereo setup, the sound has been enjoyed by a relatively small community of cognoscenti.

Now you can build yourself the Hawk Audio D-402 amplifier kit for less than half as much. Hawk, of Ledegem, Belgium, sells two kits featuring the Hypex UcD: the basic D-402, which retails for $445, and a new high-grade version that goes for $575. Both come with a power supply that delivers 40 watts per channel into 8-ohm speakers. The $575 model has improved input circuitry and more vigorous decoupling of the power supply from the signal paths.

I built the basic version and connected it to my Grande 8 speakers from Omega Speaker Systems of Norwalk, Conn. I fed it with output from my Sony NS999ES universal disk player, which I use as a transport that sends bits to a separate digital-to-analog converter unit based on the Analog Devices AD1853EB board. After a few minutes of listening I became a true believer in Class D, preferring it to the two amplifiers I'd used in the same setup—both tube amps that had cost me several thousand dollars to build.

The plastic case of the D-402 is a bit tacky, and the simple, ganged carbon potentiometer volume control will make some audiophiles cringe. Get over your distaste. Hide the amp in a closet if you must. My only regret is that I discovered Class-D audio so late. —Glenn Zorpette

You can buy the Hawk Audio D-402 kit for US $445 and the high-grade version for $575; see http://www.hawkaudio.com.