Yes, your proposal should work just fine, and I believe that similar setups have been discussed in this forum several times. You do not even need an additional amp or an A/B switch; you just hook up the two M2 "centers" to the receiver's center speaker output in parallel and in-phase. That will reduce the effective speaker impedance to 4 ohms, but the H/K should be able to handle it without a problem.

Good luck with the WAF!