I have been reading a lot of the threads concerning setup discs lately and am now more confused than when I started. I had planned to pick one of these up, along with the standard Radio Shack SPL meter, and calibrate my thratre, but now I have all kinds of doubt about: 1. the variations in levels between discs, 2. which one is "accurate" and which isn't, 3. which supports 6.1/7.1, 4. which has DD and which DTS, etc., etc. Also, why is the S&V disc so much cheaper than Avia? Is it really lacking any standard features, or is it just pro stuff. Really, all I want to do is calibrate my audio levels (for a 6.1 system, preferably DD and DTS) and establish a reference point. Is there something I'd be missing out on if I just order the S&V disc? ($22 Canadian on Amazon). Thanks, I know this subject is on the border of being done to death.