Icepower System Interfaces

The input impedance of commonly used Icepower modules is 8 Kohms. This is not a good match to some preamps. A bad preamp impedance match will probably not produce the best sound from a class D amp.

Some manufacturers add circuitry to increase the input impedance. I believe Rowland does this in the 201. This circuitry could account for the midrange qualities and missing treble noted in Jonathan Valin's review.

If impedance issues are not in play and the Class D sounds bad in a system, I would consider the possbilty that the amp is revealing a previously obscured weakness in some other system component. For example, most cd players have treble issues (IMHO) compared to the best. High damping factors may not compliment some speakers. Previously acceptable cables or speaker crossover quality might be revealed in a different light.

I also wonder if the typical power supplies used for Class D are as capable as those in the better AB amps? The use of on-board switching power supplies by B & O may be better for ease of manufacturing for an international market than for sound quality per se.

Bob