> Is there a standard for output voltage for audio
> amplifiers, or does it vary with each model and maker?
It varies with the rated power.
P=V^2/R P = power : V = Volts : R= speaker load impedance
There are some '70Volt' and '100Volt' amplifers designed for distributed
speaker systems where each speaker has a transformer that allows you to
'tap' it to set the required watts at each speaker - but this is a