I've actually noticed this too. Lowering a volume pot if you don't have a treble bleed wired into your guitar's circuit will result in less high end, which also results in less attack. But the KPA seems to respond a bit differently than a normal amp would as you lower the volume pot. Almost gets a synth-like quality to it. Or a slight auto-wah type thing but if it only went half-way. Kind of a wuh wuh wuh, instead of wah wah wah.
I don't notice it on all rigs. If I find a pattern I'll report back. Gonna try a system reset (hold system while booting to tuner) to see if that helps.
Try setting the noise gate to zero...
Try setting the noise gate to zero...
I also found when loading either FW that the noise gate was almost all the way up. Didn't notice this at first so I discarded quite a few profiles because of the strange synth like sound. Not all the profiles were like this but most of the higher gains were. Think they were profiled that way or just an anomaly? 
I also found when loading either FW that the noise gate was almost all the way up. Didn't notice this at first so I discarded quite a few profiles because of the strange synth like sound. Not all the profiles were like this but most of the higher gains were. Think they were profiled that way or just an anomaly?
This seemed to be my problem as well.
After first update to 2.3, the tones were horribly off on all my profiles. I did a system reset, and found somewhat better tones, but there was "muffling" of the sound. I eventually checked the Noise Gate. It was seriously high, and it was locked so it applied to all the profiles. I unlocked the Input, and checked each of my favorite's NoiseGate value. After tweaking some values, I found I have much better tones with 2.3.
I can't tell if all the problems are gone, but the "unplayable" tones are gone.
2.3 issues aren't just the gate. I have observed three different bugs:
1) Some rigs are sometimes "muffled", sometimes not
2) Some rigs have had the Definition parameter set to 0
3) Some rigs are actually blank, despite appearing identical to how they used to be. Toggling the Stack on/off doesn't change the tone. Gain has no impact on tone.
2.3 issues aren't just the gate. I have observed three different bugs:
...
Yeah, no one said was the only issue. It just one that several people have experienced.
