Doh! That's true. I forgot about the insertion loss. Filters are on input to amp (RCA). This is not the way to go about doing it. Never mind. Dumb idea. Thanks guys.
Valid Efficiency Test?
I'd like to measure the efficiency effects of adding passive high-pass filters into my system. I can measure SPLs (Radio Shack meter) of mains at listening seat with and without the filters (all with subwoofer off; volume knob stationary). I was thinking of using white noise signal (track from ACI Subwoofer Test CD). Would this be a valid test?