err - where did I say I had an epi? I don't want to boost treble in the EQ sense - I wonder if a germanium will give me that late Clapton/Page tone or if in a modern amp (a Vox or an Fender BJ) it will be too much?
It'll probably be too much.
As mentioned older British amps (which had very little preamp gain)darkened up and became more and more bass heavy as you drove them harder and harder. Treble boosters were great for this because they boosted the treble.
A pleasant side effect of the Rangemaster was that the germanium transistor would also break up.....you can really hear this on many of Iommi's old solos, particularily when he's on the high strings.
I don't know what kind of amp you're using, but modern sounding amps are usually voiced to compensate for this. What you may end up with is a very trebly sound that sounds like it's missing alot of bottom end.