I recently E-mailed THX and was inquiring about the exact procedures on how to use the new THX Optimizer found on some DVD's. Here is their response: Always calibrate using the 75dB SPL INTERNAL set up tone. Set the SPL meter to "C" weighted "Slow" ..never use a disc to calibrate. So THX is telling us that their Optimizer is ...what...just for looks? That Avia and Video Essentials is wrong..I am baffled? Here is another statement from the THX Website regarding their "Optimizer:" the signals used are equal to the final reference levels set during the mastering of each individual release. Thus, your system's performance can be tailored to each specific movie. As a result, you see the movie as the director intended. This appears to be a complete contradiction! Here is the Email address if anyone wants to follow up... [email protected] (Corporate Brand Manager) THX Ltd.