There's a lot at play here, Ryan... and to most of us, Sound Quality is the most important thing in our rigs! What you are talking about is going to introduce some issues. If you only have a stereo receiver, and are processing a true stereo signal, 4 speakers is likely to introduce some nice distortions in the way of comb filtering, and depending on how you set it up, potential delay issues too.
If you don't do it right, you may very well be shopping for some new gear... maybe an entirely new system!
I have two receivers and looked them up and they are nothing to write home about. I would be willing to buy a new/different one to update. How would you proceed?
Slow down, do some research, learn about your gear, and we can and will help you.