I'll chime in, based on my experience playing tonight (this morning, that is):
It's not necessarily a guitar-related or high gain pickup issue. I'm getting with my Strat using Kinman Woodstock Plus pickups. Using the CA3 Rhythm patch, and trying all sorts of tweaks to eliminate it. Then, I changed models in the amp block. Some models have more "ghost fizz" than others. Changing Modeling Modes makes some difference. It's also not a gain stage, or input/output clipping issue.
To the OP: It's the "crispies", right? Almost sounds like static. Or someone's frying up some nice diodes for breakfast. lol
I will echo some of the previous posts, in that I can't recall every noticing those sounds with tube amps (and I've owned a ton!).
So, we need to keep this thread going. It would be nice to pinpoint where exactly those sounds originate from and why. I find myself wanting to hear a more pleasing and "natural" (at least, in my experience) decay.
I'm running my Axe directly into Adam A11P studio monitors. (Really nice monitors!) And, I use Xitone cabs for live use. Of course, I don't notice it nearly to the same extent when playing live. Oh, and it's also not a volume (Fletcher/Munson curve) issue.