Objective, repeatable sound quality measurements and metrics
i dunno anything about EAQUAL or PEAQ.

judging which sounds better is quite subjective, so much so that i consider it nearly a useless question.

but if you have a reference (that you define as "good"), and you have several options to compare to the reference, and your goal is find which option most sounds like the reference, then i would recommend AB testing (a little bit different from ABX testing).  at least blind, and better yet, double blind.

the subject listens to A and to B.  as many times as they would like.  pressing A always gets them sound A and pressing B always gets them sound B.  then the only question to ask the subject is "Do these sound the same or are they different?"

put in an equal number of pairs that are truly identical as those that are the difference you're trying to test.  so for two different sounds, the subject hears AA, AB, BA, and BB.  if the subject scores more true positives than false positives and more true negatives than false negatives, he or she might very well be hearing the difference.  get lotsa subjects and have them hear lotsa different sound pairs and you can get some meaningful results.