Know of a dvd quality database/list?

I'm looking for the audio quality of a live concert set thats on dvd. Reason being there's a two disc set and a 9 disc set(4 have video, 4 are cds, one documentary). So that's double the discs for the same amount of video. One could be dual layer, but they could also be dumbing down the quality. I'd get the 9 disc one, but its a price difference of $100 and would like to know if its worth it quality wise or not.

So if you know of any sites that provide these kind of details on dvds, fantastic.

I do remember finding one years back on blu rays.

I use this http://www.blu-raystats.com/ it has a nice database with a lot of sorting options. no dvd