Hi there,
Solved the HISS in HIGH GAIN for my set. The HISS sound is like it's on the urge of feedbacking, but just not.... hopefully I described it well.
I got it solved by decreasing the DEFINITION in the AMP-section. Also it's needed to tape off the strings after the Nut and (in case of Gibson) before the Bridge so nothing resonates from those parts.
I had also 'high hiss' in numerous high gain profiles. I heard it more ore less in profiles from Cililabs, JTM, Fortin etc.
My hypothesis is that it increases when I change the original capture. E.g when I switch Cabs.
Also certain pickups are more sensitive to that curious 'high hiss' frequency. Pickups like Lace, Suhr produce less hiss , Burstbuckers and Bare Knuckles more. (I had the BKP Nailbomb set. Sold it because of the annoying Hiss..... regret that now.)
How I found out (for my setting):
I've got the unpowered Rack Profiler combined with the Matrix GT1000FX and two Matrix FR112's
I thought the problem was in the FR112 Matrix speakers. Using my headphone (Beyerdynamic DT770)......, it was still there.
Than I switched off the Cab-section. Awfull sound but concentrating on the frequencies (once you hear it, you can't unhear it)....still that Hiss.
Then I knew it was in the AMP-section. The Hiss inly deminished when I turned down the definition from 10 to 5. Don't use the compressor knob, the compressor increases the Hiss. Power Sagging etc. are (in my case) definitely not the cause.
Now it chugs without that annoying sound.
Hopefully this solves the Hiss problem for some of you.
Greetz