is it possible to use SPDIF out on the ADI-2 Pro (connected to PC via USB) to an external DAC and then analog back into the ADI-2 Pro?
I want to compare the internal DAC of the ADI-2 Pro with my external DACs, but still use the same headphone amp on the ADI-2.
Yes. There are several possible “Modes” to do that.
Look at manual page 43, DAC-Mode.
• SETUP / Device Mode/DSD / Basic Mode: “DAC”
• SETUP / Device Mode/DSD / Digital Out Source: “Default”
Then you can select the playback source for PH1/2 and PH3/4 to compare between your other DAC and ADI-2 Pro under:
• I/O / Main Output 1/2 / Settings / AD/DA Source: “Analog“ or “USB”