Nat, JC's response from Axiom appears to be right on target. On 3. in particular there may be a misimpression that the setting for the internal sub crossover(e.g. 40Hz)affects the mains if connected through the sub. The sub crossover is only a low-pass filter on its own response and has no effect on the full-range signal passed through to the mains.

The fact that a speaker such as the M80 has very good response to below 80Hz doesn't make it necessary(or even advisable)to cross it at other than 80Hz. Especially with subs as excellent as the EP500 and EP600, they should be allowed to carry the major load in the lowest frequencies which they handle even better than the M80s and relieve them(and the amplifiers driving them)of more of the load.

-----------------------------------

Enjoy the music, not the equipment.