That is puzzling. I used the test tones in the 990 to configure mine with the use of a Radio Shack SPL meter. Then I used the test tones from a test DVD and the difference was less than 1 db. My test disk is not from Avia. It is one that Sound & Vision Magazine sells. I think it was made by Ovation. It has test tones encoded in both Dolby Digital and DTS and I tried both. Are the test tones on the Avia disk encoded in Dolby Digital or DTS?