This can be done. In fact, Melco recommends it for its Switches and makes a cable for it. It's expensive compared to a standard one, but really good.
https://melco-audio.com/c1/
I have tried three types of NOS tubes: Siemens, Mullard and Philips, I prefer the Siemens. Unfortunately, these Siemens tubes are becoming more and more difficult to find and the price is going up a lot.
As far as Emile has reported, only as an output option for the XDMI card on Olympus. Initially only RCA, but they are developing XLR and it seems more elaborate.
I will comment on the difference with those supplied by Taiko.
However, perhaps my taste is not everyone's. A few months ago I ordered from Ghent, to connect my Paul Hynes and the DCD, a Mundorf silver/gold that was widely praised and yet I clearly preferred my Paul Hynes DC12FSXL cable, which...
Well, I was referring to Steve's preamplifier, but still, in general, you cannot connect a digital signal to a preamplifier. Devices that combine a pramplifier and a DAC are a type of hybrid device, but not what has always been understood by a preamplifier.