There are a few hits on this topic, but no one mentioning the specific issue I am bumping up against.
Preparing a listening space for use with a DAC with digital signal processing (DSP) includes adjusting the output for the space - which will have unique reflection/absorption of sound based on all kinds of variables from the type of paint on the walls to where/what kind of fabrics on furniture/carpet/curtains.
Software tools for doing this include Room Equalization Wizard (REW), Cavern’s QuickEQ, and rePhase. The DAC+DSP I use has an optical output connector for the data from computer.
It is possible to use an adapter cable, USB - S/PDIF, but it would be preferable to have an expansion card — probably one with the connector external to the framework 13 body à la the ethernet port expansion card — in the bandolier, ready to be slotted in at need.
I would like to see input and output for both S/PDIF and TOSLINK. Input of S/PDIF is e.g. useful for capturing digital sound from Pioneer DJ mixers.
If input and output is too complicated, than input or output which can be switched in software or by a mechanical switch it that is more practical. Perhaps even a switch with the options off/input/output