You have a time machine that allows you to watch a past event. What live music would you watch? VU at The Factory? Woodstock? GG Allin?
I would see the Mars Volta in 2003 before sound manipulator Jeremy Ward died. I don’t think there’s any high quality live recording from that era. I found this earlier vid, you can see and hear him at the start.
Honorable mentions: The Flaming Lips’ Zaireeka cassette tape experiments from the late 90’s, and any Can session with Malcom Mooney.