Kalan,
Your post is interesting since I was a Plinius SA-100 owner prior to owning the Pass. I had both amps (Pass and Plinius) for about 3-4 months. I LOVED the CAT/Plinius combo and it was a tough decision to sell the Plinius. In my opinion, those two had a terrific synergy. The only reason that I decided to keep the Pass rather than the Plinius even though the synergy wasn't as great was that I felt that the Pass was a better amp overall: greater bass extension and high frequency extension, better detail, more neutral. Plinius had a lot more slam in the bass and was a little brighter with the CAT than the Pass, but I wouldn't call it an "in your face" combo. At that time, I was using 90 db sensitivity Snell C/V loudspeakers as opposed to the 86 db sensitivity Vandersteen 3A Signatures which I use now. With the Snell's and the Plinius, use of the volume control on the CAT was frustrating due to the CAT's gain and, I guess, the Plinius high sensitivity, but when you set the volume correctly, you got a quite reasonably balanced system frequency-wise. In my opinion, the system wasn't forward or "in your face". It was more forward, however, than my current system, just not overly so.
Here are the vital stats on the Pass:
Pass Aleph 4
Gain: 26 db
(unbalanced)
Sensitivity: no rating
Input impedance: 10,000 ohms
(unbalanced)
I don't doubt what you hear, Kalan. It is surprising that such a sensitivity mismatch would affect one set of frequencies as opposed to others, since I interpret "in your face" to mean an overemphasized midrange.