I just tried Volumio 2.348 for Sparky with USBridge, and it does not support my KEF X300A speakers properly over USB. I think this may have something to do with the Linux kernel revision for this build being 3.10, which lacks a specific patch to work around a known firmware bug in the X300A. By comparison, Volumio builds for Raspberry Pi and PC work fine with the X300A, by virtue of these having later Linux kernels so the X300A patch is in place.
Separately, I also tested the USBridge with the latest DietPi (v159) which has the same issue as Volumio, though with DietPi, I got my X300A working properly after editing /DietPi/uEnv.txt file to set “aotg.aotg1_speed=1” and rebooting.
Is there a plan to update the Linux kernel of Volumio for Sparky, or is there is workaround available for X300A?