Unfortunately, you are among the many that have finally discovered this truth. Bose has just done a fantastic job at marketing hype.
You aren't kidding! This system is going to blow you away! I'm excited for you.
Back in the day, receivers had A / B before "Surround Sound" was introduced. Honestly, there is no benefit or reason you should need to use 4 speakers up front when listening to music. You may find that you prefer to listen to all 5 speakers when listening to music, some prefer to just change a setting in the receiver to Stereo so that only the front to speakers and a sub are playing while other use a "Direct" setting which often plays only the front two channels with no sub playing. It's all about preference. Sorry...I just re-read your question and it appears you want to have both the front and rear speakers playing when listening to music. No problem. Most receivers have either a "Music" setting that will play all 5 of your speakers, there is another setting called "All Channel Stereo" (I don't prefer this setting). Once you get your receiver setup, you can go through the different sound fields to see what your ears prefer most. Your receiver may have a Zone 2 but that is more for having the receiver play a 2nd set of speakers in another room (say the patio or pool area).
Yes, as long as your receiver has pre-outs for all 5 channels, you would connect RCA out of your Receiver's Preouts to the Inputs of the Emotiva. Then speaker cables from the amp to your speakers. If your receiver has two sub outs, you can connect one to each sub. If it only has one sub out, buy a "Y" adapter and connect both subs to the single sub out on your receiver.
I tested it once with my setup and heard no sonic benefit. Your amp will be MORE than sufficient for your 5 speakers and has a much larger power supply than your receiver will have.
I use 12 or 14 gauge wire from Monoprice. Super inexpensive (also for interconnects) and great quality. I love banana plugs just for convenience. They offer no sonic improvement or degradation of sound quality. Merely nice if you plan on switching speakers in and out.
I just looked at the rear of your Denon....it has preouts for all speakers. So you would connect 3 pair of RCA Cables as follows:
RCA Cable 1 (Red "Front" Output to Input 1 on XPA-5, then speaker out to Front Right Speaker)
RCA Cable 1 (White "Front" Output to Input 2 on XPA-5, then speaker cable from XPA-5 to Front Left Speaker)
RCA Cable 2 (White "Center" Output to Input 3 on XPA-5, then speaker cable from XPA-5 to Center Channel)
RCA Cable 3 (Red "Surround" Output to Input 4 on XPA-5, then speaker cable from XPA-5 to Surround Right Speaker)
RCA Cable 3 (White "Surround" Output to Input 5 on XPA-5, then speaker cable from XPA-5 to Surround Left Speaker)
You made an AWESOME jump! Well done!
Thanks a lot for all the great feedback and info!
I'm pretty sure I've got it. One thing I'm still not sure of though-I have two RCA pre outs on the back on the AVR per channel (other than center) and only one input on the back of the XPA. Do I only use 1 from the Denon? Also, what does balanced or unbalanced mean?