I recently E-mailed THX and asked them how best to use their new THX Optimizer. Thx's response was this: Never calibrate using a DVD disc. Only calibrate using the internal test tones in a receiver or pre-amp. This is in direct contradiction to their statement regarding the THX Optimizer: THX Picture and Sound Optimizer (THX Optimizer) is a unique DVD software feature from the THX Digital Mastering Program that allows you to optimize the performance of your home theater system for individual DVD titles. THX Optimizer consists of a series of tests that make it easier for you to fine-tune the audio and video performance of your home theater system. But best of all is that 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. Can anyone clarify?