iPad to Dac through optical/coaxial?

I have an iPad to stream music through a Schiit Modi external DAC to my Yamaha A-S701 Receiver connected with a USB cable. Since I beleive the built in DAC of my newly bought receiver is better than my Schiit Modi, I'd like to pass the digital audio signal directly from my iPad to the built in DAC of my receiver with either an optical or coaxial cable.

I'm looking for a simple interface that has a USB input and and coax/optical output, and passes my signal without conversion. I am thinking something like this Douk interface, but with a certainiy that it will work with iOS as well. Or anything that would do this job. Is that even possible?

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