The problem with car subwoofers and home stereo is that you need a high power amp to get good punch from a subwoofer. Car amps don't work because it is impractical to generate the 12VDC required. The hi-fi you have may not have a low pass output to filter out the frequencies the subwoofer can't support.
Most home stereos are not 3ohm compatible. That is very low impedance for home audio equipment. Some pre-built home stereos have 3 ohm speakers but they are designed for the speakers they are sold with, not generic speakers.