Can power amp chips be bridged in parallel?

[R.G.]

I believe that "Rem" is short for "Remote". I think some car audio stuff relies on the main tuner/preamp/whatever to activate them. I ...think... that means raising the remote activation line to +12, but this is very much more tenuous, more like speculation.

The instructions that came with your amplifier will tell you what that wire does; should be in the 'installation' section.

[defaced]

R.G. is correct.  Car audio uses permanently connect B+ and ground with an enable wire that gets held to B+ to turn the device on - that's your Rem connection.  This allows high current amplifiers to be turned on/off via the small switch mounted on the back of your ignition lock cylinder which couldn't handle the 10s of amps needed to power the amp.  If you pull the pinout for the radio's wiring harness, this connection should be pretty obvious.  Most DIY repair manuals (Haynes, Chilton, etc) have a schematic section in the back - look there, or see if you can find one online.  If it's not obvious which pin is the remote connection, post it up and we'll see if we can identify it for you. 

Or, if you want manual ability to turn the amp on/off, just wire a switch from the remote connection on the back to the amp to the incoming B+. 

[PRR]

REMote must connect to a +12V source to turn the amp on. In a car, this comes from the "power antenna" lead which raises the rod when you turn on the radio.