I agree with zumbo & jaxvon... if you have the luxury of having the information as to what it was recorded from, then by all means. Then again, I sometimes flip through the many formats, "just to see".
And what about 4.1 ? Since someone brought up DSOTM, there was a 4.1 Alan Parsons Quadmix that's floating around the internet somewhere, I actually have a copy. (email me if you can't get a hold of it...) Now, that one's a tricky one to tell the difference between that and the 5.1 remastered SACD, through all the formats. Maddening. I've spent a decent amount of time trying to figure out why Floyd didn't go with that one, but some say 'the politics' of the time. The SACD is better in my opinion.
Anyway... blah, blah, blah.
nasd90