I also have Cubox i4 pro + Volumio and have played around with a few usb dacs. I’ve had success with usb with a Behringher uca202 (very basic but handy device) and a Consonance Box-1.1 (24/96 spdif converter). I’ve NOT had success with Yulong U18 (a Tenor chip TE8802L async USB), nor have others using devices with this chip as documented here:
I would love to get a fix for this problem. The U18 does works out of a EDO modded Squeezebox Touch (which has a later Linux kernel) so in theory it should be doable on Volumio with a kernel upgrade. The U18 async USB sounds good – with Foobar/Win XP (where the Yulong supplied drivers work just fine) it sounds a tad warmer and clearer than the Consonance on the Cubox (I’m running both the AES/EBU (U18) and coax (Box 1.1) into the same Dac for easy comparison). But that’s just my system & personal preference, and on some material the Cubox/Consonance is preferred. As always, YMMV.
I strongly recommend you check this “Raspberry Pi usb Dac compatibility list” as a very rough guide (I doubt the Cubox hardware will be any problem; potential issues from my experience are a Linux kernel/driver issue – my kernel is “volumio 3.0.35”; its possible the Raspyfi kernel is later than that (I no longer have a Pi around to check).
[raspyfi.com/raspberry-pi-usb ... rted-dacs/](http://www.raspyfi.com/raspberry-pi-usb-dac-and-raspyfi-supported-dacs/)
Looks like the 2nd device you mention should be ok as its usb is a TAS1020b and that appears to be working.
Best of luck with whatever you decide. Hope the above helps a little.