Very cool, really good and naturally sounding plugin. I still am using the older JAMP and AMPER amp sims from Analog Obsession. Better than a lot of commercial amp plugins and for freeware top-notch. This one is even more flexible, maybe could offer a little more gain, but I help myself by stacking two of them, mostly M-JTAMP and CUSTOM. You can use an IR behind, but for me it already sounds good even without one.