Thanks, JohnK. (any axiom tech online to confirm ?)
Kcarlile - my reason for asking went something like this (it might be a naive/not-very-useful one but it is a reason ;-) ):
say, instead of the value of 300hz given by johnk for the woofer crossover, it was 150 Hz (as in the case of B&W DM603 S3). Since my receiver has a fixed sub crossover at 100 hz, I get some idea of how much or how little work the woofers on the M60 would be doing when the sub is hooked up.

btw, if the front speakers are configured as "large", does the receiver send the "full range" frequencies to them or does it only send the frequencies above the crossover setting ?

cheers.