I've been trying for the last couple of days to profile my 5150 III 100S and have had a terrible time trying to get an accurate profile.
I'm running the head into a 4x12 loaded with Greenback RI speakers (an old Egnater cab from the days before Rocktron and their modern offerings) and I've tried a variety of mics through a Chandler TG2 preamp or straight into my Roland-Octa Capture.
Interestingly, I was able to get some great profiles of my Egnater TOL100 (which I'll be testing, tweaking and sharing soon if they sound as good at the gig as they do at home) even on the highest gain settings... but even at the highest gain settings on that amp, it cannot compare to the gain that 5150 will put out... it's a beast.
With every scenario I tried (with the 5150,) the resulting profile had considerably more high end content and a somewhat "phasey" character to it. The low end and more scooped mids of the 5150 just weren't there.
I tried "refining" several times and played dozens of chords for several minutes. And while it got closer, it just never got there.
So I guess this question is for you guys that have done these super high gain profiles... what's the trick to getting them to come out right?