I have no experience with the X1 Preamp, but as a long-time ham radio operator and having built some clocks and digital displays, and working a lot with computers (display drivers are basically a small compter of sorts), I would suggest that in a less than perfect design the digital display drivers could generate noise or "hash" that could get into the D and A circuits at some point. There are also small caps around the chip or chips that make up the display driver hardware that could be missing (factory defect) or have failed and now be letting some noise out that otherwise wouldn't be a problem.
Hence I'm not surprised that you are hearing the display in the preamp output. If you can live without the display while doing serious listening, I would turn it off.
Hclarkx
Hence I'm not surprised that you are hearing the display in the preamp output. If you can live without the display while doing serious listening, I would turn it off.
Hclarkx