Difference between THX Ultra2 and THX Select

Archived from groups: rec.audio.high-end (More info?)

Hello,

I was looking at buying an onkyo 7.1 receiver for my home theater.
Some of them are called "THX Ultra2 7.1-Channel Digital Receiver"
(TX-DS989ver2) and some are called "THX Select 7.1-Channel Digital
Surround Receiver" (TX-NR901). Is there a difference between these
THX formats?

Would you recommend any other receivers for a home theater set-up?

thanks,
bala