afgverhart

I had exactly the same issue with my AVM V30 pre-amp/dac. Exactly the same behavior and I was not able to get it to work with this High Sierra version on an OS level. iTunes did not work, Roon did not work and also Audirvana. It seems that some type of USB receiver chipset used in DACs is not supported by some later High Sierra versions. I ended up downgrading to an earlier High Sierra version (trying hard to recall which version, will post it when I recall) for it to work again. I was lucky to have a time capsule backup that I could use for this purpose. I will try to find which HS version worked still for me. You can also install the initial HS version on an SD card, boot from there, see if it works, install update, see if it still works, update again, etc. this is what I did to find the ‘bad’ HS version that caused the issue. BTW: this issue was one of the reasons for me to change DAC... edit: found it:

Well, it’s not a fact at all in my setup. The Hypex NC400 kit based mono amps are outstanding.

If you are willing to try this, maybe first try this on an SD card to see if it really fixes the issue. Or alternatively, install an older version of Mac OS on the SD card that you know worked before. That worked for me.

Well, I can confirm that Mac OS High Sierra solved the USB DAC issue for me. My AVM V30 now works correctly over USB with Roon running in integer exclusive mode!

Anyone tried High Sierra already? And did it solve the issue with USB DACs?

I have decided to slightly change my setup. As I am using a headless Mac Mini i7 with two hard drives, I decided to stick to Sierra on the one drive (planning to update to High Sierra when then becomes available) and on the other drive I have now installed El Capitan (instead of running it from an SD card). This setup works flawless and I can choose which OS to boot from. So if High Sierra would solve the issues, I would be able to continue using that version. I make regular backups from Roon to be able to restore my latest Roon database in 'the other OS' as I obviously had to install Roon in both OS's on both drives. Edit: additional advantage is that by having both drives backed up by Time Machine, I always have a full system backup available being able to restore both installations.

No updates yet. Maybe (hopefully) High Sierra will solve this issue.

I haven't given up yet. Installed MacOS El Capitan on an SD card together with Roon Server. Works perfectly: full USB functionality including exclusive/integer mode in a Roon. So I can now dual boot the Mac Mini: El Capitan for audio from SD and Sierra for the other stuff from HDD.

I have considered your solution as well, but think this might be too difficult for me.

Well, I am able to use USB audio output with Mac OSX Sierra 10.12.6 again, but Roon still is unable to connect to my DAC/preamp when set to exclusive/integer mode. I am now considering to install Mac OSX El Capitan on a SD card and boot the Mac Mini from that card. This will be an audio optimized version of El Capitan with only Roon Server installed. This way my OSX installed on the hard drive can remain up-to-date (to check if future versions of Sierra or High Sierra solve my issues) and I will have a working 'audio mac' available by booting from the SD card.

According to the CEO of AVM Apple will fix this in the next Sierra release.

@Sam Lord Do you have a picture of the layout that you prefer over the layout that I used?

This is how the wiring of the Hypex nCore looks in a Ghent Audio enclosure.

Really interesting to see how taste and preferences can differ from person to person.

The modules and power supply are from Hypex: nCore 400 and SMPS600. The case and wiring are from Ghent Audio in China. Great cases that look beautiful and are engineered in a perfect way.