I just set up a standalone GigaStudio machine. It's a 2.53 Pentium system with an M-audio Audiophile 192 in it. 1 Gig of RAM. Host machine is a 2.8 Gig Sonar system with a MOTU Traveler in it (nice box, by the way). I'm running a MIDI cable to the 192 and wanted to run digital back.
When I cable back to my Sonar system with SPDIF, I get several dropouts, clicks, and pops. When I go back via analog, I get much, much fewer (although still too many...should be 0). Of course, I went into the Delta control panel on the GS machine and bumped up the sample buffer. No effect on the SPDIF problem.
Anyone see a reason why I wouldn't get the same level of continuity on both interfaces?
Do you have BNC cables running from your soundcards to a master clock (like a Big Ben or something?) If not than make the MOTU card your master clock and make sure the M card is getting it's clock from the MOTU via BNC cable. Also make sure ALL your related software is setup the same way.
You will get clicks and pops with both analog and digital with bad clocking exactly as you described (i.e. digital always worse than analog)