I have been comparing both and just wanted to confirm what I believe I hear.
I think the Monoprice 8320 sounds better by a substantial margin. 8320 is capable of producing music which sounds more "live" and personal.
My first thoughts were that the Sony sounded like all the other IEM's out there, while the 8320 has more tonal separation and custom quality sound. The Sony sounds muffled by comparison.
Is it just me or does the 8320 actually sound better?