You'll probably need to go into the receiver's setup menus, and setup the system, for the equipment you're hooking up to it. The main setting in the dvd player's menus, you need to set, is to set the audio output to "Bitstream", and not PCM. Then set receiver on "Digital Auto". Not familiar with Onkyo, so don't know their terminology.
You
may need to activate the surround speakers, set the distances, and set the levels, for all the speakers. May need to turn center channel "ON", or say "YES" for center. With center channel "off", you'll get a "Phantom Center", from the mains. You'll probably need to turn "ON" the sub, and set speakers to "Small", if you have one. If you don't have a sub, set the speakers to "Large", so the LFE (bass) signal will go to the speakers woofers.
Take your time, and go through the process in your owner's manual, step by step.
Good luck!
BTW.............
Don't waste your money on Monster cables and wire!!!!!!!
You can get very good 12 ga. speaker wire at Lowe's or Home Depot. See here for cables:
http://www.bluejeanscable.com/ or Radio Shack, but don't let the salesman at Radio Shack talk you into Monster cables. They make a good comission on them, because they're so expensive.