It appears that the center speaker channel on my ADA1000 has gone out. There is no sound coming out from every setting on the receiver I've checked. I tested another center channel speaker in the same output and nothing. Any help would be greatly appreciated. It's a 5 channel ADA1000

Have you proved it's not the center channel of the receiver that failed?

No, I'm afraid I don't know how to do that. I suppose plug the center channel speaker directly into the receiver?

Before you do anything drastic, confirm your rca cable is ok. I once thought I had a bad channel on an outboard 5 ch amp, it was the cable.

Do what Adrian said by swapping a known good cable. Then do what I said by putting a channel (eg. Right channel) into the center input of the ADA and seeing if it plays. If it does, the ADA is ok and that channel on the receiver is bad.

It's just a speaker cable I bought from Axiom, but point taken. I'll change out the cable after I test by putting the center speaker in a known good speaker channel.

It was indeed the RCA cable!!! Thanks so much Adrian and Mojo. Now, I've got to go buy some higher quality RCA cables. Funny, I've never, ever had an RCA cable go bad on me. I'm 62 years old and been messing with this stuff for longer than I care to admit....
Thanks again!!

I'd say that's very rare but glad you're back in business.