Want to take it to the next level?
Change from USB to Ethernet playback using a good player software like Linn Kinsky and Minimserver. This smokes anything USB and optimizations are simpler than with USB. Here is my comparison:
https://www.audiocircle.com/index.php?topic=155232.0
Interchange is one way to get there:
https://www.audiocircle.com/index.php?topic=156409.0
Also, try comparing your FLAC file to the same wav file. Change it to wav using DBpoweramp on PC or XLD on Mac. If your system is up to it you should be able to easily hear the difference.
Steve N.
Empirical Audio