Hey guys,
Thanks for all the responses so far! So yes I do own Mbritt profiles, and they do sound much better than most. I also own his stuff for the Atomic Amplifire. I think one of his "tricks" is that in his cabinet IR's he really lops off the top end pretty low, probably around 6k Hz , maybe lower. That doesn't leave room for high pitch noise , well because there is no top end ! And yeah his tones are great for cleans and mid gain stuff, but not really a fan of his high gain pack.
So I plugged my DT 770's into the Kemper headphone jack and I do hear the harshness.
Here's a quickie clip from a ChopTones profile of a TSL Marshall. It's not the worst sounding one, but while I had a spare 10 minutes did a quick clip. But when you play for say 30 minutes your ears get really fatigued listening to a top end like this.
Maybe it's just a profiling thing that you need to take care of the high end, or decapitate it like MBritt does ?