I guess layering 2 pre-amps will help but don't find the best match.
i find the 200, 350, 500,600,800,1500,2500,3000,4000,5000,8000 areas problematic
Yes using a DI, -18dBFS.
For post EQ, I start rolling off under 90-100Hz, with a slight bump at 100Hz if needed to emulate cab woof. Maybe a narrow dip around 700-850Hz if it's too honky. Slight wide dip 1k to 2k to make room for clean vocals / piano / strings. And then do surgical narrow cuts in the 4k to 8k region to remove digital and annoying fizz, usually around 4.8k and 5.2k in my case, and again 7.2k maybe (depends on your setup). I just make a narrow notch and sweep until an annoying fizz goes away, then adjust the Q and dB so that it's reduced but not totally absent.
If you're going to layer guitars, I recommend using completely different amp sims instead of the same exact one atop itself, otherwise it starts sounding too phasey. You can make one with less gain and more low-mids than the other to add some body without increased fizz.