The response from Axiom makes sense to me. The EP350 and EP600 will have different input sensitivity ( one will need more gain than the other) due to the amp design. Using them together in a multiple subwoofer setup will ultimately make calibrating more difficult. This is one of the advantages of using identical subwoofers.

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne