"Rick Curtis" wrote in message
om...
Steve,

The easiest way to do it without a switch is to use 1N4004 diodes on
each of the four speaker wires where you hook the two sources to one
speaker. This will keep the signal from going from one source to the
other source. If you don't know what I mean, let me know and I'll
send you a simple wiring diagram.

That will definately NOT work. You will protect the amplifers all right, but
you are effectively rectifying AC current, resulting in very bad to no audio
at all.

To get technical: in series with the output is a large capacitor that is
charged to half of the supply voltage of the amplifier. This voltage stays
at that level, because the average voltage and thus the current though the
speaker of an AC signal is 0. If you now put a diode in series with the
speaker, the average is not 0 anymore because positive current is passed and
negative current is blocked. First, this distorts the signal heavily.
Second, it causes this capacitor to charge to full supply voltage, until no
current is flowing at all anymore. No current = no audio.

Meindert