what does the Kitsune Audio su-1 DDR interface actually do?

Evening Goners!

I hope one or more of you can shed some well needed light as to what this product is literally designed to do and how one would pair it to the Kitsune Audio 3 "Spring Dac"??
Also, having a headphone amp, CD player and streamer going into my GamuT amp and preamp combo, is this piece even needed?
This would be for NON COMPUTER listening except the Tidal app on my iPad...
Thanks so much for all that take the time for a "digital rookie'!!
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