Stereo & Electronics - factory Monsoon amp

Does anyone know what the factory amp part number is for a 1993 Firebird with the Monsoon sysytem. My problem is the whole left side set of speakers quit working and the guy at the audio store thinks its the factory amp. So I took the amp out, and have the same symptoms. All right side, no left. Also, the aftermarket subs only work with the remote cable removed. With this cable connected the left sub doesn't work, but the right one does. Any ideas? Pioneer aftermarket head unit. Factory speakers (except the subs).

Are you sure it had a Monsoon amp? I don't think they put them in until 97 (there was a Bose option before then so that might be what you have). You said even after removing the amp you still had no sound on one side? Honestly the issues sound like they may be from your head unit. You said the left side of your subs don't work when you connect the remote wire? Is this also connected to the headunit?