HIDDEN AMPS:
• (1) `60’s Vox AC30TB converted/customized to a head – reference tone for FOH (w/Vox 2x12 cabinet [located behind rack])
• (1) `50’s Fender Deluxe Tweed (mic’d at rear)
• (1) `60’s Vox AC30 (mic’d at rear)
FENDER - BLUES JUNIOR - (Customized) - Xxxx - Used for shimmer effects during Vertigo tour.
FENDER - Deluxe - 1959 (Behind rig during 2005/2006 Vertigo tour._
HIWATT:
HIWATT - [model / information forthcoming]
HIWATT combo amp - [model / information forthcoming] - Mentioned as being used for "Elevation" during the "All That You Can't Leave Behind" recording sessions.
Neat! Thanks. Yeah what's the deal with the amps behind the main rig? Backups? They need to be isolated

You can see some of them here

He used the HiWatt on ATYCLB for Elevation, right? You can also see one in a picture of HQ during Atomic Bomb recording sessions in U2 By U2. What's your opinion on HiWatt amps, Jeff? I saw Oasis a couple of weeks ago, Noel Gallagher is using HiWatts exclusively for this tour. I thought he got an awful sound out of them, I wish he'd switch back to his Fenders and Voxes of yore. Yet we see Edge has gotten a killer sound out of HiWatt amplification.
I assume the Vox-in-a-box refers to the amp kept in a box so the soundboard can get a sound w/o the ambience of the room/arena, right? Dallas makes some mention of it in one of these videos from the Elevation Tour (anyone else seen these?)
PART 1
PART 2
PART 3