http://www.homecinemachoice.com/cgi-bin/outputpdf.php?file=HCC/136/056_HCC_136.pdf
THX tearaway gets a tune-up
The advanced RoomEq system lurking in Pioneer's updated AX4 THX receiver
is a double-edged sword, says a straightjacketed Richard Stevenson.
...
Conclusion
Out of the crate and unfettered by EQ, the AX4ASi has every feature you'll need and is better balanced and more potent than its predecessor. The clever MCACC EQ system is a double-edged sword, teasing you and then robbing you of weeks of your life as you fine-tune it towards crafting theoretical perfection in your room. Then the missus goes and moves a pot plant... what ya going to do? AV propeller heads will love it.