Don't go out of my way to listen to Dweezil - I certainly think he is very talented. Thought the tour of the equipment was very cool.
[VIDEO]http://www.youtube.com/watch?v=jRXnPcIK1V8]YouTube - In the Studio with... Dweezil Zappa[/VIDEO]
That's quite a rig, but this video is already out of date. Dweezil hucked all that rack stuff and now gets his sound from two Axe-FX Ultras going direct to the PA. Apparently, transporting that rack around the world got to be a bit much, and some of the vintage stuff in there that Frank used is far too fragile and irreplaceable to go on the road.
I read somewhere that Frank spent the modern equivalent of about $200,000 in the early '70s to develop his guitar sound. There wasn't nearly as much specialized gear back then, and he ended up using lots of pieces designed for studio use to get his sound. He also used a switchable multi-amp setup long before anyone else thought of doing that.