I have a HPF on my iAmp Classic...it's subtle - so much so that it's always on. Not sure if it's the subtle rolloff or perhaps the frequency it's at.Also, see the Ultra Lo switch, when set to “cut”, it cuts at 40Hz. Would you compare that to a HPF somehow? I would imagine it could help cleaning up the boomy low-end….
The cut on the SGT is NOT subtle. I felt the 810 Cab sim was excessively boomy and wanted to use that to tweak it, but from flat to cut it really took most of the air out of the balloon.
Instead I'm going to edit the roll off for that Cab in the Ampeg Editor digitally.
I could see it being useful if I'm sending a post and direct signal to the FOH to be blended, otherwise just not my cup of tea.