I only use one input with the Cyan 2 - the I2S so it is not an issue for me.
One thing to keep in mind with Denafrips is the ladder resistors directly drive the output. So you want to use the balanced outs. The single ended is not as good as it runs on half ladder only.
If you must use single ended then Holo Audio Spring 3 or some other DAC with discrete circuit to drive the output. I can also highly recommend the Fezz Audio Equinox tube DAC designed by Lampizator. The version I have is the single ended only model. Sounds amazing for the price. But is not R2R if that matters.