THX is processing added on top of DD/DTS, not instead of. The THX spec means it has processing as well as the amps are capable of delivering ref levels in a ~2000 CF room. My receiver is THX select, but I never use the processing because I don't like the way it sounds.
I'm with John. THX merely extrapolates a 5.1 signal putting it into 7.1. I've messed with it on my 801 (set up for 7.1) and results have varied with different movies depending on the encoded track (DD/DTS). For some reason, and it may be my imagination, was that THX post-processing on a THX certified DVD yielded better results than a normal DD disc.
THX-EX processing will create 7.1, but regular THX posprocessing still has an affect on 5.1 material as 5.1. I don't use it in general, because it seems to roll the highs off a bit. I agree it varies from movie to movie, but rather than check each one, I just leave it off.
Thank's for the reply, i just wanted to know. Reason for is because i've hearded it in goodguys and it sound real crisp & clear. So is this receiver worth it or not. Or do i get a DENON, which one is better anyways i've heard different views from both ONKYO,and DENON.