From Schiit:
Clicking When Changing Sample Rates/Pausing/Etc.
1. It’s totally normal for our Bifrost and Gungnir DACs to click (mechanically, from the chassis) during normal operation. That’s the muting relay, doing its job. It clicks whenever the SPDIF datastream is interrupted.
2. If it’s clicking excessively on a Mac or PC, you can reduce it by routing system sounds to the speaker on a Mac, rather than to the Schiit USB Audio Device output. On a PC, you can set system sounds to "no sounds." In both cases, using USB largely eliminates it.
3. If it’s clicking excessively on a CD transport when in pause, the CD transport has a cycling interruption in the datastream. There’s no real fix for this, except getting another CD transport. It won’t hurt the Bifrost or Gungnir, though—the relays are rated for several million cycles.
I have the same combo as the OP, and yes, it clicks frenetically when the transport is Paused, something I now do very infrequently.