I have acquired a NAD C320 BEE amp which I believe suffered a period of running on low impedance speakers due to someone trying to run too many speakers in parallel. The C320 seems to work perfectly well on all functions and although the output is very weak on both channels, there doesn't seem to be any distortion. I've checked the pre-amp by taking out the links and checking output with a scope , and fed the power amp section with a tone generator - still the same results, low power. It's almost as if there is a mute or a protection circuit engaged. Both of my speakers and cables work perfectly by the way. And ideas folks?