it would never shut off but then when the car gets shut off the power just gets cutoff that sounds bad also
This shouldn't be a problem. Some people have reported loud pops when the power (ignition) is shut off, but that can be fixed with a bit of electronics (Resistor between sig/gnd on RCA output, ISTR).
I wouldn't recommend tapping it to battery (unswitched) +12v, unless you plan on ALWAYS taking it out of the car when not in use, or you have a few spare car batteries.

_~= Dearing =~_
"WAY too happy about having #99."