Is it alright to place the 350 on top of the 500? I didn't know if it would hurt the sub if it's vibrating when pumping out the bass? I'll try that. Is the bracing in the 500 sturdy enough to hold that?

Thank you for your help Chris, I'll try your other suggestion too to see if that will work!

2 = M60,4 = QS8's,1 = VP150,1 = EP350,1 = EP500
HK247
Optoma HD70,110" DIY screen
Xbox360 & PS3