Have you played with the "Audio MIDI Setup" control panel? Do a command+spacebar to search for it.
If you getting it working, consider purchasing the "BitPerfect" app for $10. Really made the USB sound out of my MBPs much better.
Then once you are ready for more, consider a step up to a Roon Nucleus or other server. The sound was clearly better (lower noise floor) than two different MBPs+BitPerfect. Install and run Roon on your MBP first to see if you like it and if it is worth the money to you.