Audio system question - not upgrade

[jpc763]

I noticed today that there did not appear to be any sound coming out of my door speakers. I have a 2001 S with upgraded sound. It has the CDR 220, dash speakers and door speakers. I used the "fade" mode on the radio to try to isolate the door speakers but when I faded to the back, there was no sound at all. Balanced or front seems to only provide sound from the dash speakers.

Is there separate fuse for the door speakers?

Any other things you can suggest to figure this out?

Thanks, John