Can a multichannel amp (5 channel) run at different ohm levels? I'd like to run my front and rear channels (1+2 & 3+4) at 2 ohms but I only have one 4 ohm sub so I can only run channel 5 at 4 ohms.

yes

Before you heed Russell's simple one-word answer, you should do more research. What brand is it? What does the manual say? If you don't have the manual anymore, it's usually posted on the bottom of the amp (all the ones I've worked on anyways). Never assume anything to be true with amplifiers. One screwup and you have a nice smoldering hunk of burnt electronics. <BR> <BR>Trash <BR>

Thanks for the word of warning -- I've already installed it and decided to just run everything 4 ohm across the board -- it's got plenty of power for the speakers but the only problem is the terrible engine noise that I'll be trying to fix this weekend! Thanks!