Amps only power on one side

If you have two amps and have only one side on both,its probably not the amps.Are using a preamp.Could be that! Whatever your amps are going too. Re-check you wire connections at the speaker binding post and from your amps and or preamp.Sounds like something isn't connected right.Its very unusual to have both amps losing one channel at the same time...I would loook for a bad coonection somewhere. Possibly a fuse????

This is kind of a long shot but if you have an internal short in either the speaker or speaker cables on one side you could have blown out the same channel on both amps when you tried them one after the other. I mention this possibility because it happened to me. In my case, it was a short inside the speaker cabinet caused by a loose speaker terminal.

If that's what happened and your amp has fuses to protect against a short it's an easy fix to find the fuse on the circuit board and replace it.