Ah, a 40Hz crossover and still clipped the XPA-1? I'm pretty surprised. Perhaps one circuit can't handle two XPA-1's? (we are talking about 2000w here). Just out of curiosity, how does one check for line sag? I hope I never need to, but in case I do, I'd love to know how to go about it.
Tells you the power draw of the device, line voltage and a host of other things. You can find out what devices are real power hogs even when in standby etc. and just how much power the amps drew while watching Transformers at Reference LOL.