Originally Posted by wiffleball
I'm looking for an AVR with speaker calibration that will run 4 ohm speakers (M&K) comfortably, and was wondering what the difference is between calibration systems. Is audyssey the best?
Depends. Audyssey comes in several varieties with different levels of sophistication. The other inbuilt systems are YPAO (Yamaha only), MCACC (Pioneer only and in different varieties), Trinnov (Sherwood and ADA only at the moment). RoomPerfect (McIntosh only at the moment) and ARC (Anthem only) are in prepros (which solves your 4 ohm problems) but Anthem is unveiling a series of AVRs at CEDIA.
But here's the rub: What's best also depends on the room/setup/speakers, the patience/sophistication of the user and how much personalization he wants. I have only used a few of these but all in the same room so the results may not be generalizable.
So, no answer but the broad base of Audyssey implementations is strongly in its favor. Just get the XT version, imho.