Steve,
May I make a few suggestions.
Have you talked to anyone at Burr-Brown
about A-to-D and D-to-A converters?
Have you talked to anyone at Audio Precision
about using their test gear?
Have you read any of Julian Dunn's white papers,
he did some work in this field and
worked for AP before his untimely demise,
but I think you may be able to downlaod his papers
off the web for free.
Have you talked to anyone at Anagram Technologies?
That's the technology that Manley Labs used in the SLAM.
Speaking of Manley, have you talked with anyone there?
My own wild ass guess is that we will get better sound when the speeds are drasticaly bumped up and the bit/word is increased to say 32 or 64 bits. I could be very wrong, look at Sony and SACD's specs. 1 bit at a million miles a second. LOL. Maybe I got it half right cuz with Sony, the speed is there.
One thing is sure, there is room for improvement, otherwise there would be no debate going on of "analog vs. digital." Although it is getting better all the time, I fear the debate will rage for some unknown amount of time.
Who knows, maybe it has something to do with the effect of heat on the sound or some other weird behavior that no one has yet noticed or measured. Science got us to the moon, but it has not yet cured the common cold nor ended the problems in the A-to-D and D-to-A debate.