BoB- Just a 2 ch CD with different freqs in different tracks. So for example to test phase, I can play an 80 Hz tone with an 80 Hz crossover, then swap the phase (input) on my sub and compare levels. (I use the Autosounds 2001 #101 disc. Has individual tracks for 10, 11, 12, ... 98 Hz.)

I test it either digitally to the 950 via coax (using the 950's digital crossover), or via the 5.1 inputs using the analog crossover. (But it's just a 2.0 signal that gets converted into a 2.1 signal by the 950's crossover.)

So with the digital input, using the positive polarity input on the sub, the sub is in phase with the mains. Then I switch to the analog input, and the positive polarity input goes out of phase, and I have to switch to the negative polarity input to get the sub back in phase with the mains.