I am running Onkyo's 800 series Receiver & DVD player through the larger of the QX line of Dahlquist speakers. I am not convinced THX is such a big deal. I have been experimenting with the THX mode and it always sounds like someone tossed a blanket over my system. I am VERY happy with my setup but I am finding the THX mode useless. I even a complaintif comment stating it means "TURN" around and "HEAD" for the "EXIT". I did not purchase the Onkyo for the THX certification. I'm glad. Can someone explain to me what is supposed to be happening when one selects the THX mode?