This review by Robert Deutsch answered all of my questions about CD playback with a PS Audio PWT. The answer to my original question, is yes, it is worth it to splash for the latest DAC instead of the older MkI version. Thanks all, mission accomplished.
http://www.stereophile.com/content/ps-audio-perfectwave-directstream-da-processor-robert-deutsch-feb...
http://www.stereophile.com/content/ps-audio-perfectwave-directstream-da-processor-robert-deutsch-feb...