My new Metrum Acoustics contains a USB unit that is not recognised by EC but was by the previous version. The manufacturer of the USB part is working on a solution and the issue has been mentioned online in audio forums as affecting more units than just Metrum.
I'm having to use SPDIF for now which hopefully will be OK. Has anyone else experienced similar? I read that it is to do with Apple 'tightening up' the USB specs in EC. Whatever that is.