I have the PS Audio DL III and I do not recommend using the USB input without placing a USB/SPDIF reclocker in the path before the DAC. The DL III's USB implementation does not produce very good SQ compared to the toslink/coax inputs. The difference was easily heard in my cheapo system.
In fact, the USB input of the DL III is limited to 16/48, so if you want to play 24/96 or 24/192, you must use the DL III's toslink or coax inputs.
All that being said, the same USB/SPDIF re-clocker can also improve the SQ of your toslink and coax outputs from the Mac, if the re-clocker has those inputs.
In fact, the USB input of the DL III is limited to 16/48, so if you want to play 24/96 or 24/192, you must use the DL III's toslink or coax inputs.
All that being said, the same USB/SPDIF re-clocker can also improve the SQ of your toslink and coax outputs from the Mac, if the re-clocker has those inputs.