I usually use headphones with a correction curve in the Global EQ, and I like how many of the presets came alive with Cygnus. But today I've been playing thru my Mesa 20/20 and 2 4x12 Recto cabs, since nobody's home... I disabled the EQ, but I leave the Power Amp Modelling and Speaker Cab Sim on, and I just scrolled thru the first 50 presets, and easily 25 sounded great to me, albeit with that Recto cab flavor (but I like that for now.)
So I don't know what to say other than have you checked the basics: You know, everything? Fresh strings, good cable, Power Amp Modelling and Cab Sim ON, latest FW..., you don't have the Global EQ set to something weird...? Have you loaded the updated presets?