I don't have a super expensive setup (obviously relative), but the difference in 320k mp3's and flac are very obvious to me when played back on a Consonance 120L CDP...yet 5 years ago using a Yammie HT Receiver they sounded the same....so you're answer may lay in your pre/amp setup as opposed to the source. Just my two cents, YMMV
L'wood
L'wood