Hello James.
I’ll reply to your post, but I’m not sure my form is any better since I don’t have an answer for you and am going to link to my thread in Audio Products.
I’m having trouble getting a Schiit Eitr (which also uses their Gen 5 USB tech) to work in exclusive mode with my mac. The Eitr doesn’t have manual controls for setting sample rate and bit depth, but per @Adam_Woodbridge’s suggestion I did that in Roon. However, while my settings in Roon called for a max bit depth of 24, Audio MIDI still showed 32 and I was unable to change the mac’s setting to anything else. There was some talk over at head-fi that the usb controller’s accepting a 32-bit device might cause this.
I don’t know if that helps you or not, but I’ll drop a notification for @support to see if they have any suggestions. If you have any, I’ll gladly take them.
Roon Ver. 1.3 (Build 242) stable (64bit)
macOS Sierra Ver. 10.12.6
Mac mini (Late 2014) 2.6 Ghz Intel Core i5 w/8 GB of 1600 MHz DDR3 RAM
Mac --USB–> Schiit Eitr USB/SPDIF Converter --Coax–> Schiit Modi Multibit
(Edit: Corrected link to head-fi)