maybe some of the brittle culprit but i'm not buying that argument in general.
i can use the CHEAPEST cabs and power on great tube amp front end and make it sound warm and tube-like. but it doesn't work the other way around.
maybe a valvulator in the loop of the axefx would help. my friend recently picked up this UA preamp:
and it turned her taylor guitar tone from thin and brittle into something wonderful.
one of these in the loop of the axefx, or maybe a fractal/atomic designed interface box like a dumblelator loop box, to insert in the loop of the axefx, may be just what the doctor ordered.