Your best option is probably SPDIF digital out to DAC. USB limits you to 16bit, 44Khz. With Spdif you can go24/94 or higher.
Another option is the $150 M2Tech Hiface gadget. Converts USB - SPDIF (RCA/BNC).
Another option is the $150 M2Tech Hiface gadget. Converts USB - SPDIF (RCA/BNC).