I can't go any higher on my EMU 1212m mixing software, the SPDIF is at 0db. It seems like on my rig, 'tickling the red' output led gets me into the special place where most rigs sound glorious, but this does not clip my SPDIF at all. It just sounds better.. I don't understand what is going on, but maybe more people can try it and see what they find.
Overall loudness vs dynamic feel are totally separate and distinct. You can have an extremely dynamic feeling tone but super loud as well. I don't really enjoy guitar tones that are dynamic like a piano, ie, extremely soft and loud sounds. I do enjoy tones that float between clean and dirty depending on how hard the player digs in but this shouldn't have to do with the output volume generally.
Quotebut my RME has a mixer software that allows me to boost the SPDIF playback volume. I use this to make the KPA stand out enough against the Mix in my DAW software.
See, this is exactly what I don't get, why do I even need to boost the KPA to make it stand out.. I shouldn't and don't after tweaking the Cabinet volume.