Check out the gear the guys are using on tour.
Brad Whitford's Amps
The second PRS amp is an HXDA, which is designed for a Duane Allman tone and is run through the second 4x12 onstage. Also part of the tonal equation is the Fender Twin Reverb Custom 15. It's been customized to run a single 15" Warehouse speaker which is housed in a custom cabinet. He prefers the Fender for its clean sound with clear low end.