Rule of thumb

The rule of thumb is that you should spend about 2-3x the cost of the AVR on the speakers as the speakers are the most important component in your setup. It's a general guideline and won't necessary apply to an entry level setup where the 5.1 speaker setup might cost the same amount as the AVR. The main takeway is that you are better served putting more of your available budget into better quality speakers and a lower quality AVR then the reverse.

My research says that you are spending about $600 on speakers.

The first thing that jumps out at me is the absence of a subwoofer which is IMO absolutely mandatory with speakers this small. A good entry level subwoofer like a Polk PSW 550 would provide a significant sound quality advantage, even if you just bought a bottom-end AVR such as a Denon AVR-1612 refurb at

http://usa.denon.com/us/product/pages/refurbishedproducts.aspx?catid=refurbishedprocat(denonna)&catalog=denonna_us .

It appears that AVRs tend to all sound alike (just fine). Other than obvious features like network connectivity and on-screen menus the one thing that can make a clear audible difference is the nearly-universal availability of an automated system tuning facility, where you set up a mic at your listening location and the AVR adjusts levels, etc for the best possible sound quality.

The difference between Audyssey Multieq and Audyssey Multieq XT32 is aside from the obviously upgraded features, the most potentially audible reason to purchase a more expensive AVR:

http://usa.denon.com/us/product/pages/productdetail.aspx?pcatid=avsolutions(denonna)&catid=avreceivers(denonna)&catalog=denonna_us&pid=avr2113ci(denonna)