justboom digihat, volumio, and external asynch DAC

I’ve been using volumio for a few weeks now and I’m impressed. I’m using USB out to an external DAC connected to a fairly high end system (parasound JC2 preamp, mark levinson monoblock amps, martin-logan CLX full range electrostats). The sound is gorgeous. I know there are issues with pi USB, and my slightly aged bryston BDA-1 external DAC only supports USB 1.1, but the bryston is well engineered and has an extensive reclocking architecture, which likely addresses some of the USB jitter issues. However, I wanted to try adding a clock board to the pi with tos or spdif output to the bryston DAC. I’ve read the I2S discussions, and find them convincing. This would also address the bryston USB 16 bit limitation. So… I purchased a justboom digihat. I can’t get it to sync with the bryston via either the coax or optical connections. In playback options, I find I have to select I2S dac to get the digiboom board to show up, so I guess volumio sees the clock board as a dac. But then, after selecting the digiboom and rebooting, I get no audio. After a couple of reboots and fiddling, volumio seems to have gotten confused. I could not return to USB playback: had to go back to factory setting and re-index to continue. So, a long message, but my question is 3-fold:

  • any configuration I should be doing for the digihat beyond whats on the playback options page? (I’m comfortable with OS changes via ssh if needed)
  • any issue with digihat syncing to a reclocking external DAC?
  • suggestions for other solutions for spdif to external DAC (preferably I2S based)?

if it helps, here are the relevant bryston BDA-1 specs:
dual 192K/24 bit CS4398 DACs
synchronous upsampling at 176.4,192K (turning upsample on/off does not affect lack of sync)
sample rates 32,44.1,48,88.2,96,176.4,192
16-24 bit PCM, 16 bit 32-48K USB