Sorry, MarcK, I don't understand your point about a low end A/D converter at all, and loss of quality from it?

The whole point of digital out is that there is no analogue stage whatsoever until you actually play the music through some loudspeakers. This will either be through the D/A in your soundcard, or more likely the D/A in your audio CD player, after you have made a CD, and many audio CD players have higher quality converters generally speaking than most soundcards (excepting some high end soundcards).

There is no A/D involved at all in the keyboard - that is the whole point of digital out - not having to convert to analogue and then back to digital again and then back to analogue again, with all the potential additive degradation that involves.