There are 4 mono tracts on the stereo past masters. ( presumably because they couldn't separate anything from the original tapes ) and they give a nice clean ambiance in Trifield, but with no disrespect intended what is the point of the monos? There were only 10,000 of the box sets made and they've sold out so they will probably make more. But is the sound purer and cleaner? Just curious. I have the first 4 CD's in the older mono versions and the 6 disc anthologies that came out in the mid 90's and i'm not sure i'll ever listen to them again, but never say never.