A mate of mine has asked me a question about his amp, that I did'nt know about, so I thought I would ask you guys, as I was wondering the same thing

He has a 4 channel Boss BA-2900 (1000watts peak) that he uses to drive a single sub. Now he was wondering, by driving one sub in bridge mode, and no other speakers attached to the amp, if the remaining power on the amp comes back to the one sub? Or is a 4 channel amp, just like having two, two channel amps built into one?

This would only get the power from the two channels bridged.
I'm not even sure if any multi channel amps are bridgable to one channel. ie 4 channels to 1.

All I know is that in some reviews they've shown that say a 4 channel amp with 2 channels being driven might yield 100WRMS but with all four channels being driven it might only yield 190WRMS or 195.

I'm not sure makes for this loss, a 4 channel amp is like 2x 2 channel amps in the one casing, with one power supply.

Thanks heaps for the reply!