I do have an audiolab mdac plus and happy with the performance.
I have tried two different connection from my Win 10 desktop to MDAC.
1) SPDIF output (Optical). My PC does not have RCA digital out.
2) USB out. For this I installed an audiolab driver and selected that in Foobar.
I found the sound quality slightly better in option 2. When I play a FLAC file it shows PCM 44.1 (Option 2) against the SPDIF PCM 192 (Option 1).
If anyone knows any other option to tryout, please share.