Can you hook up a car amplifier to a home stereo amp just to play music not for power to car amp?

Possible, but not without doing a number of other things first that would likely make it not worth it. For one, car speakers are typically 4 ohms, sometimes 2 ohms or even 1 ohm. Home theater speakers are typically 8 ohms, but sometimes 4, 6, or 16 ohms. The impedance mismatch can overwork the amplifier, possibly causing it to overheat or blow the speakers. The use of resistors or wiring speakers in series to alter the impedance is theoretically possible, but often results in very poor sound quality. Car audio requires a 12-volt DC power supply, whereas home audio requires the local mains voltage (for example, in the US 115-volt AC, 60 Hertz). While you are probably familiar with small transformers that plug into wall outlets and output lower DC voltages, a power supply that can provide enough power to run an amp could cost even more than an amp designed to run on AC mains power.

if i understand you question right, no u cant when u go from home theater to car audio there terms like amps and watts are the same but used in different context. if u really knew what u were doing by adding resistors and capacitors and such u might be able to, but i wouldn't recommend it. also a car amp only use 12volts to power and a house power is 110 volts so say good bye amp if u plug it in.