take a digital multimeter and measure the end of the rca cord using AC voltage setting. heres a hint when measuring, turn up volume at least 75% of full volume to take an accurate measurement. most headunits dont even put up near the rated vrms power until the last few clicks of the volume, but by then the signal has already gone way into clipping and lots of distortion and whatnot can be heard. i think theres only a select few headunits that actually didnt go into clipping when turned all the way up, but i dont remember which.

ombastic... do you happen to have an rsx by chance?? or visit clubrsx? i think ive seen the same screen name on there.