I have found that tube amps do not do well with a heavy gage cable.16 or 14 gage is best.
Tube Amps and Cabling
I am contemplating purchasing a VAC integrated tube amp to replace my solid state integrated amp -- when I can afford it. Do you have any experience with the effect of this kind of change on cabling -- from solid state to tube amp? Did your cabling sound appropriate after the change or did the change require you to replace any cables?