The Vox in a Box is mic'd and ran direct to front of house. Being in a box, there is little to no bleed in the mid from other amps. That is blended in with the other mic'd amps to obtain the tone for various sections of the songs.
For shows when the band and their own crew are using their gear, their soundboard (vs the gear of say - The Letterman show) and where O'Herlihy has the final say and do over everything sound, they pull out the stops. Full rack. Full array of amps, including the Vox in a Box to blend in with the other tones.
But for a TV, awards or promo show it doesn't work. From an FOH perspective, Joe probably isn't using his own board. There may be less spots on a TV shows board than what he uses for a U2 show. Also setup time and such are limited when it comes to awards, promo and TV appearances. Hence, things are boiled down to their essence.
For the Tibetan Freedom concert in 1997, Edge used a pedalboard. Why? Probably due to time constraints of the show and change-over between bands, this is probably why this set-up was used (pedalboard, amp, guitar)
As a sort of example of this approach, the 1997 Tibetan Freedom Concert.
Not often you will see Edge use a mere TWO guitars for FIVE songs. And the fact he used TWO guitars and not one, was probably as he felt the need to have the 12-string Rickenbacker for "Gone" and "Mysterious Ways:
In this case -
- No rack - pedalboard.
- A couple of amps.
- 2 guitars and 2 guitars. 12-string Fireglo Rickenbacker and `75 cream LP Custom Interesting in that Edge hadnt used the LP Custom for "One" up until this point (He's used the Gibson 330 (ZOO) and Country Gent (Popmart). Also, his use of the LP Custom instead of Country Gent for "Please". The Gent had been used for all the Popmart shows, but for this he use the LP Custom and the MTV Euro awards he used the Gibson 330 TD.
GONE - LP Custom
U2 - Gone (Tibet Freedom Festival 1997-06-07) - YouTube
MYSTERIOUS WAYS - Fireglo Rickenbacker
U2 - Mysterious Ways @ Tibetan Freedom Concert 1997 - YouTube
ONE - Interesting bit being that it is of the first times I remember seeing Edge use the LP Custom for One. ZOO TV was the Gibson ES-330TD. Popmart tour was the Country Gent
U2 - One @ Tibetan Freedom Concert 1997 - YouTube
UNTIL THE END OF THE WORLD / BREAK OJN THROUGH - LP Custom
You can gets quick peek at the pedals at about 2:40 into the UTEOTW clip.
U2 Until the end of the world live 1997 New York - YouTube
PLEASE - (4:30 in you see the pedal board but it isn't a clear enough shot to make out all of what is there)
Played on the LP Custom, vs. the Country Gent (used for all Popmart shows). But that said, he used the Gibson 330TD for the MTV Europe Awards
U2 - Please @ Tibetan Freedom Concert 1997 - YouTube