@itsjustme The power cycling entailed the green LED on the preamp
rapidly alternating from green to red. The LED on the amp was
simultaneously doing the same thing.
Every time the power LEDs
switched to red, the sound was distorted through the speakers, sort of
harsh and "buzzy". It was as if the system were being driven into
clipping, but at a low volume. It was similar to the sound of a poorly
tuned FM station.
That is very strange. Why would two independent products have the same odd behavior? Let's assume the LEDs indicate power (green = on, red = standby?) and are triggered by various power supplies. Its also odd, to me, that two very different products have the same LED arrangement and trigger on the same phenomenon.....
The only thing that I can think of is a power anomaly. If power, for some reason, was rapidly browning out and recovering, it could do this. If (AC) power were to fall and recover, the power supplies would fall and become noisy, which would in fact create hum and low-volume clipping (since the rails would be lower clipping would occur nearly immediately).
But why and how would this occur? Beats me. Some kind of power line short? maybe. But i cannot be in either box or surely they would have foudn that at the factory.
The chance of both failing simultaneously, int eh same way is near zero. So it is either a) exogenous or b) one of the components affecting the other.
I think you have a 3rd issue to find and fix.
G