Well I spent the last day or so toying with mine and I can say with confidence that running the Pi through USB to an MF Vlink and then to my Rega DAC gives the best results by far. No messing with any settings or tweaking of volumes on the device required.

As such I'll be offering my IQ DAC and case for sale here and putting the Pi in a case in its own. Fancy one of those wooden ones actually. I just can't get away with the sound of the IQ DAC... definitely not my cup of tea.

Anyone interested in an IQ DAC and case is welcome e to PM me...