[jbclem]

I have a VW OEM car stereo cassette radio. 4x20 watts. The speaker
impedance is 4-8 ohms. I only use the front channels and have the fader set
to front. I keep the balance in the middle. This radio has never had much
volume, but recently it's even lower, to the point that if traffic is noisy
it's hard to hear. I've known for a few months that one speaker wasn't
working, and just found out it was a wire that had slipped off the connector
on the speaker. But I've been using the radio for months with this speaker
disconnected and I'm wondering if this could have affected or damaged the
output amplifier stage.

Is there a measurement (millivolts?) that I can take from the speaker wires
that would help troubleshoot this. And is there anything I can do to
further check this problem. The speakers are only 4", so they should be
overwhelmed with the volume control on full, but it's not even close to
doing that.