So can the SQ playback FLAC over the USB connection? Or do FLAC files need to be converted to WAV first? Or neither and FLAC will have to go through an external D/A converter and then into a line input?
I imagine if your DAW supports FLAC it could import the files onto tracks and playback might be possible from the DAW through the USB-B connection. In that case the SQ would be receiving audio signal via USB, and not actually reading FLAC files.