having trouble with my PV 900 amp

Im having trouble with my PV 900 amp. I have it hooked up to my vestax midi, and Acened speakers. I can play a song and hear it through the speakers, but there is static. Also, My midi has an output level, and when I try to mix up a song, there is only something coming out of the RIGHT output. I know its not the speakers because I switched the ACR cable from white and white and red and red to white and red and red to white. When I do this, the other speaker that wasn't working before worked and the other one dosn't.

I think this is an audio or output setting, or a mono switch is on. I need help ASAP because im having a gig this week and I need to solve the problem to have the best quality.

Please help.

Thanks in advance.