I had the same problem! I was using an old computer feeding a Lampizator Dac. I tried a newer computer (2 years old) and problem solved! In my case the popping noises were due to an old USB architecture, so perhaps you should try another computer and see if your problem goes away. Cheers!
loud intermittent pops from DAC, possibly related to long USB cable from computer
when I bought my benchmark DAC 3 years ago, it made loud intermittent pops. people suggested it was due to the long USB run, so I got a 'USB active extender' 15 ft. cable which connects to a regular 15 ft. USB that goes to the DAC. the problem stopped - until now: I recently disassembled my system (changed the cabinets). when I turned it back on, the pops were back (fwiw: they only happen during the music, not when it's idle). I tried turning off the DAC, disconnecting and connecting the cables, but so far no luck. any ideas?