George,
As an Esoteric K-03X owner, I have played around quite a bit with Esoteric's filter and up-sampling settings (which have been carried forward through several product generations). As you may know, an unfortunately a long break-in period is required for each filter/up conversion setting. I found that the default settings of no filter, no up conversion resulted in very detailed but to my ears somewhat etched sound. Ultimately I settled on 2Fs up conversion and the SDLY1 filter. YMMV. Probably the best discussion of the various settings that I've seen can be found in this review:
http://www.theabsolutesound.com/arti...-k-03-tas-213/
Looking forward to your further commentary.