I was trying to diagnose the odd surround effect i was receiving with DPL II and i needed to turn off my main speakers. Just by unplugging them you can get a real idea of the sounds that are sent to the surround speakers and really understand how 'supplementary' they are.
It was a neat effect to hear only the surround output.
We did the same for the subwoofers during the SVS and Axiom comparison. Again very interesting to hear only the bass notes during one's favorite song.

"Those who preach the myths of audio are ignorant of truth."