Excellent link, there are some noteworthy points on there.

-they recommend setting the sub crossover at 10hz ABOVE the lowest freq. the towers can cleanly handle(M80s, we know, can reach quite low).

-they seem to lean more towards a lower(than 80hz) crossover to not localize the subwoofer location.

-it sounds to me(maybe I'm wrong) that Audyssey set my mains to 'Large' and at 40hz because they can go deep, cleanly.

I may try a crossover of 60hz tomorrow, at 80hz, I'm sometimes able to tell where the sound is located. As has been mentioned, some recievers only have the default setting of 80hz where others are more flexable, so I'll tinker with this some more.

Thanks for the link, Doc, it's very helpfull and informative.

Half of communication is listening. You can't listen with your mouth.