copper foil caps...?

[clarkydaz]

anyone tried copper foil caps in their amps? expensive, but may be worthwhile for the tonal benefit. i have a couple in my les paul, and for kicks i put a sozo in to see how they would compare. really suprised how flat they sounded compared to the copper foils, switched back immediately. wondering if the same principle would be evident in amps. if so what caps on the board would have the most significant effect on tone?