Center and fronts are omage impact
Rears are polk audio m1
I can't find anything useful on the Omage speakers. The Polks are rated to 85Hz @ -3dB. I would set the crossovers for all speakers to no lower than 100Hz - although, to be safe, 120Hz might be better.
Denon doesn't have an AVR-1315, although I do see a PMA-1315R
. Perhaps you mean the AVR-1513?
If 'yes', go into the speaker set-up menu (see the manual for how to do this) and set the crossover levels for all speakers channels to 120Hz. If you also have the option to adjust the "LPF of LFE", make sure it's set to 120Hz. (If you don't have that option, don't worry about it - it's probably "hard-coded" to 120Hz anyway.)
My sub is a powered pasive sub
A passive sub is basically just a box with a driver in it, powered by either an external amplifier or, in "budget" cases, by a powered subwoofer channel in an HTiB (home theater in a box) receiver. If your sub has a built-in amp - I suspect it does - it's an active sub.