Pioneer Receiver
Expect the performance of the 815 to be closer to that of the low end Yamaha you are returning. Also check the Audioholics review of the 815. Since it sounds like you live at home and have a small room, the 815 would provide more than enough power.
The 1015, however, is a big step up in terms of quality, performance, and amp power. It is also a THX Select receiver. If it is in your budget, go for the better model. You can find it online for around $400.
If you are not opposed to the Yamaha brand, the HTR-5860 would make a good upgrade. It has pre-outs, 7 channes, auto setup and EQ. You can find it online for about $300 from authorized dealers.