Based on my two weeks with a pair of TacT S2150 amps, be sure to check out the Equi-bit units too. They seem to be equally good as the ICEpower amps. And they accept a digital signal -- i.e. no outboard DAC or analog interconnect. Volume control is totally out of the audio path, as the voltage of the power supply rails can be reduced for signal attenuation. Very, very cool!