To be sure, you want to use the A500 for music and the Denon receiver for everything else?
It will not be possilbe to connect the speakers to the receiver and A500 and use them one at a time. If you are thinking of using the two sets of binding posts at the back of speakers, the receiver and A500 will be shorted at the binding post and will cause problems since one will feed Line (or speaker) level signal to the speaker connection of the other, depending on what is powered up. You can probably put a 2 way switch in this manner and make do... see attached image.
If you use the receiver pre-outs, the A500s will drive the speakers at all times.
Why do you need the EQ? The Denon has the Audessy EQ system and the ability to manually tweek FR.