DIGI2 PRO V2.2 + DSP with external I2S input

I would like to send an I2S signal to the DIGI2+DSP from an external source (i.e., not from the Pi) have the audio processed by the DSP and then output on the SPDIF of the DIGI2 PRO.  I will always be running it at a fixed, known sample rate (e.g., 192KHz).  How can I do this?  Here is the GPIO diagram and what I think I need to do:

i.e., Disconnect the lines from the Pi to the DIGI2+DSP for the clock select and I2S as indicated, and on the breakout of the 40-pin header on the DSP card, drive the clock select lines to the right values and supply the I2S signals on their respective lines.  Is this right?  What else do I need to do?

I am hoping to retain the ability to use hifiberryos to reprogram the DSP and to use the equalizer GUI to adjust the DSP parameters -- but just have the I2S come from an SPDIF input interface that I am adding.

Thanks for your help!


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