I'll be running it between 4 different DACs' HP amp outs and the LCD-3s, using 1/4" TRS in the headphone out section on the DACs to the 3.5mm line in on the switch, and then plugging the LCDs' TRS plug into the front TRS jack. All of the DACs will already be hooked up to the computer via 7-port powered USB hub or optical out, being fed by J-River Media, which can supposedly feed multiple USB outs at once. Then to compare all I have to do is turn the nob on the switch... right?
For the analog end that feeds your LCD-3, yes - just turn the knob.
I can't guarantee what will happen with the digital "switching" you've described, but it sounds feasible.