Marantz 2240 Reciever - PA

I bought an old Marantz 2240 Stereophonic Receiver because of its modular construction. I took out the power amp section to replace the power amp section in a blown power mixer I have.

I got everything out and hooked up right yet the sound is distorted. I suspect there is some kind of input signal problem. Does anybody have any idea on how I could correct this?

Thank you,

Benjamin Linford