I just bought an Up2Stream Pro to install in a tube preamp (Bottlehead Smash, built from a kit several years ago). I’m planning on adding the DAC board for improved audio quality, but I may also want to add digital input capability. Since both of the add-on boards utilize the same connector, adding both boards appears to be impossible. Am I missing something?
What you are proposing is possible, this post may assist you: Up2stream Pro V3 and I2S output
Note that some modifications are required to the ribbon cable to allow both to be connected.