Have you tried Sozo's in a Marshall yet Lew? It's funny this thread has just come up as my Sozo caps order came today and I've just fitted them (replacing the Mallory 150's) in my Marshall. In terms of sound difference, I was surprised by how noticeable the improvement was, your tone sounds much clearer (without losing gain), and there seems to be less extraneous noise (although to be fair that could be because I did a better job of the soldering joints). The quality of tone is just better, it's not something that's easy to describe, it's not like the frequencies have shifted, but some aspects of the guitar sound that were undesirable have just gone. Sozo caps are definately worth putting in your amp if you've got a Marshall.
