Honestly, I have a denon 3311 in which has audessey xt and also has an onyko 515 in which has audessey 2eq. And ran audessey on same place using same speakers and I dont hear any difference. In fact I am able to hear better the surround effects from the onkyo than the denon 3311.
I ran audessey again and tested the same movies (batman, battleship and avengers) and i hear better the surrounds effects on onkyo. The warmer and cleaner audio from denon is a plus. The audessey xt is supposed to eq the sub. And all i can tell is that after running audessey my sealed sub sounds more tight on the onkyo while on denon bit deeper.
The onkyo 616 has few advantages over 515. One is that has manual eq for speakers and also 4 additional low frequency bands to tweak your sub. Also it has 3 stage inverter amps, 20w more per channel, and thx.
I also own a yamaha 471 and ran ypao on same place with same speakers and i have to say that the onkyo 515 with only audessey 2eq sound much much better than yamaha. Oknyo is a power beast. Pretty loud.
The only audio correction that i havent test is tbe pioneers mcacc. So I ordered a pioneer sc-1222. Im neutral in this things. Most people says that audessey is better. But im pretty sure that the advanced mcacc is on par if not better than audessey xt. I ha e to prove it myself on my enviroment. I will test all my receivers and then will post my impressions. The thing of mcacc is that after running calibration you can tweak everything and is not too straight forward. On audessey you have to do nothing. Omce audessey finished its calibration is done.
But i like to tweak so, it will be a nice experience.
My speakers are Polks RtiA7, Rti4, CS20 with an Emotiva Xref12sub. Having said that dont be affraid of the 616. I did not bought the 616 because i thought that the 515 has manual eq, but its not. For me manuak eq is a plus. My idea was to returned the onkyo and get the 616, but I decided to returned when pioneer arrives so I can perform tests again. Also im not interested in thx at all. In the past I had an onkyo 706 and i remembered thst i have 2 differents eq for sub. One setting is which sub sounds deeper and other in which sound more tighter.
Om your price range I will look on onkyo 616, or pioneer 1122 or one of the Denons if you really want at least audessey multieq. But for me I cant tell you that multieq xt is better on my ht room than 2eq. On paper is better; in reality Is another story.