Raspberry Pi hardware is not the fastest out there, and it doesn't play every codec out there, but no other hardware receives anything close to the A1++ support and attention to detail that we see from the Pi Foundation staff to ensure Kodi runs great. The on-board audio is nothing special but there are a huge number of i2s DACs available, and there's no reason why the USB device you already have shouldn't be usable.
Thanks Chewitt, it is exactly the support and volume of Raspberry users (General/Kodi/Volumino) that makes me want to go back that road. Since my current DACs USB interface (Also open source (Audio Widget)) work with no extra tweaking on CuBox I don't see why It should not work Raspberry if the first versions USB ethernet congestion problems are cleared out. And I cant see why it should be an issue now, when RPi is on No 3 and 4 years later.