splitting stereo tracks to mono -- audio quality?

[mcconnellsteve]

if i split a stereo track into two mono tracks (panned hard left and right), should i hear a difference in quality? i tried this as an experiment for fun and i THINK i am hearing something different, but i'm not sure if i'm psyching myself into that or if there really is a difference.

on a related question -- let's say i had a stereo piano track that was recorded without compression and my only outboard compressor is a mono unit. would purists cringe if if i split the stereo track into two mono tracks and then processed each of them (individually) through the outboard mono compressor (recording them back in through two different mono tracks)?

thanks,
steve