Jafox,
I certainly agree with you about the CAT amps and resolution - they are among the finest resolvers of low level detail I have experienced in my system.
However, it looks like we are talking past each other here. Yin and yang in my understanding always have been accepted terms for describing frequency response characteristics (i.e. there is no amibiguity in their meaning, such as with prat - which really is related to transient performance - or with continuousness, which I think relates to dynamic performace across the frequency spectrum). Typically, yang refers to a frequency response that is tilted toward the whiter side of the spectrum. The extreme of yang is clinical (or as you put it, analytical), cold, sterile (in fact, your identification of the CAT Amp and preamp combination is a perfect of example of the yang side). Yin refers to frequncy response that is tilted toward the warmer side of the spectrum - the extreme of yang is referred to as dark, fat, tubey, etc.
Thus, to rephrase my previous comments in more acceptable terms, my system tends to lean more towards the analytical side of the frequency spectrum than yours, which is why I think the Aqueous would work better in my system than yours. Further, your identification of the Aesthetix premps also matches my initial perception - I think anyone would say the Callisto is certainly more towards the yin side of the spectrum than, for example, the preamp in the DCC2.
I also agree that "decay" is important - although decay is also a result of transient performance, low level resolution, and, depending on exactly what one means by decay, microdynamic performance. It is these latter two qualities that are most important for me. If a system cannot provide resolution of low level detail, and does not excel at microdynamics, I become bored with it rather quickly. I thought the Aqueous did an exceptional job with these characteristics without leaning two far to the analytical side of the frequncy spectrum (and hence found it have the best balance of characteristics that are important to me).
As to the Opis, as I think about it, I probably committed the same error I cautioned against - I only gave them about 50-75 hours or so before I gave up on them. Did they change singificantly during break-in as well?