I also agree, you could always add the amps later... try the H/K alone first, you may find it easily handles the job.
By the way, that is going to be one NICE system. M60's 4 QS-8's EP 500 and the VP-150 all powered by the 7300 should be SWWEEETT!!
How big is you HT room? Did you consider the M 80's? I only ask because they have the same power handling capacity as the other speakers.
Also nice choice on the H/K as it gives you good bass management options.
Be sure to give a review and pics once your set-up!
