I've wondered about the quality of embedded load features on various amps (ie: in my little H+K - may explain why Lucas chooses to use XLoad, or as you mention, maybe some just don't like some coloration inherent in the two notes). Anyway re the "Double Note Load Box" spkr curve, afaik, it would emulate a 2NoteLoadBx / Speaker interaction when p.a. modelling on + typically with IRs or SS Amp + physical cab, BUT, personally, I'm running Axefx power amp modelling off (which disables the spkr curves) when running my load box'd physical amps into Axfx since there's already a cooking power section in the tone from the loaded physical amp output (power amp modelling ON would overlay that which I don't want). Just my basement hacker's preference/2c ("AxeMaster" only because I stumbled upon the mighty Axefx many moons ago and spend waay more time posting here than I should

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Congrats on the amp! - I'd love to have one also but don't think I could sneak something like that in without my spouse spotting it.

(maybe I can swing a G20 tho!)