Quickest and easiest way would be to resave all 49 presets, with x4 enabled.
Cumbersome, but shouldn't take very long.
Keep the original INI if you want to revert to x1.
This plugin is amazing
Seriously .. I've stopped using IRs because I'm really loving the speaker sim on this beast.
I can't believe how versatile it is.
Crystal clean to scorching death metal.
Some of my fav presets:
Van Halen 1
Super Bright
Mark 1
Hi Gain
Triaxis
Rectifier
Pantera (this one sounds exactly like Vulgar)