Well since everyone else has input...
You apologized for different volume levels.
I believe that changes everything in evaluating the pre-amps.
We can all hear that sample 2 is darker/deeper/warmer/muddier or however you want to define it.
I felt the darkness of sample 2 was exactly that and more of that than warm so I voted for 1 which sounded more clear.
While agreeing with a previous post that people often flock towards the brighter sound, (example: Most run of the mill radio listeners will crank that treble up), and while I had this exact same thought when listening to the 2 tracks, I feel we must be careful not to shy away from the brighter if it in fact sounds the best.
I heard a MAJOR difference between the two, but as far as telling which preamp is supposedly better, I would say that is near impossible, if not due to the MP3 format, the sounds chosen source, and level differences, then due to the fact that neither of them sounded any worse than the other.
You HAD to expect all the critism and suggestions, didn't you?
Well heres some praise. Great and entertaining idea. Thank you for the time and effort. It was fun to compare the two.