10.13.2 still not seeing my USB Schitt DAC

No worries... I assume you have tried to power it off and on, even if it via the mains? I would try changing the USB port where it plugs in the iMac + power off and on + restart a few times. I am in the UK btw, so perhaps we have different models of the Modi 2. Also, sorry mine is actually the Modi 2 Uber which explains the presence of the metal switch!

You may want to contact them yourself.

http://www.schiit.com/contact/help-support

My guess is it needs a firmware update which they may not be able to accommodate. Or you may need to downgrade to a version of macOS that's compatible.

Problem solved.... I literally switched the Modi 2 DAC OFF from the back i.e. the metal on and off switch next to where the USB cable goes in to the DAC. BOOM - It just showed up in "Sounds" in the OSX preferences and works now! 🙂

Note, I did change USB port it was plugged into in my iMac this morning and restarted. I wonder if that helped - not sure. It definitely didn't work UNTIL I switched it off and back on...... Who would have thought!!!! ....reminds me of the "Press 'any' key joke"... anyway hope this helps!

FWIW, the current version did not claim to fix an incompatibility with the Schitt DAC in particular. Did you contact Schitt?

What did they say? I have exactly the same issue with my Schiit Modi 2 on OSX High Sierra 10.13.2...

Good find. You may have to do that each time you shutdown, restart or put your iMac to sleep. Hopefully not.

Did you try contacting them?

http://www.schiit.com/contact/help-support

Which model do you have?

Modi2, Bifrost, Gungnir or Yggdrasil?

Tested - works even if I restart the iMac i.e. no need to restart the DAC 🙂