I picked up from try Anastasio's rig.
Someone posted this in a Phish page:

Brad Sarno posted (1/20/98): "I hear so much talk abou Trey's amp but really, for the most part his tone gets formed well before the amp. The most overlooked device of all is the Ross (not Boss) compressor pedal. In my opinion it is THE secret weapon of his tone. If you ever plug into one you will go "aaaaah". There is no other compressor that sounds like that. It is this pedal that lets Trey go from a single note to a full chord and have it all come out full and even and sustaining. His guitar doesn't really sustain that well, but with the compressor he can add sustain and also induce feedback easier. The key also is that the tube screamers come before the compressor. This lets Trey turn on a tube screamer, turn down the guitar volume to control the distortion level, and the compressor keeps the overall volume nice and loud and even. This is probably why he gets away with having the Tubescramer's volume on 10 without sounding so loud when he kicks it on. This evenness that the compressor provides, lets Langudoc keep him real hot in the PA without fear of suddenly getting too loud."

Then there was sound