Thank you to everyone who has responded, you have all been VERY helpful! So let me see if I have understood everything correctly. Of course my ultimate goal is the highest sound quality possible. I believe I do know the difference, have more than one "serious" audio system and have the empty bank accounts to prove it!
The computer running the Asus ST CAN use a Musical Fidelity up-sampling DAC, but I have decided not to use it since it only supports 24/96 in/out and so it is relegated to my headphone system. All audio and DAC will be handled by the computer/ST.
I have a decent collection of high-bit-rate FLAC's, right up to 24/192 so getting bit-perfect processing with minimal re-sampling is desirable, if that is the best route to go.
Note: I am currently using the Xonar Unified Drivers, 1815 v 1.64 beta, in low latency mode.
"The Asus ST automatically re-samples all incoming sound to the sample rate set in its control panel"
(1) Is this in reference to the Windows setting shown in the screenshot? If so, which would you say does a better job of re/up-sampling? The Asus ST card itself, or MC, if I want to re/up-sample everything NOT 24/192 to 24/192?
(2) Although I have not done any serious A/B testing myself, would you say that re/up-sampling anything NOT 24/192 to 24/192 (either in the ST or MC) improves, or degrades sound quality?
(3) If I have set upsampling in the Windows settings (screenshot) to be done by the Asus ST, does that mean I should DISABLE output formating in MC? It looks like I am re/up-sampling twice based on the screenshots? Once by the ST and then again by MC?
(4) I suppose my basic/main questions are about the "best" or suggested way to get the best sound quality possible, with no external DAC, using the Asus ST with lossless FLAC's ranging from 16/44 to 24/192?