Thanks to Reg for this link where Kirk Hammet from Metallica talks about playing with Tool in Hawaii. Here’s an excerpt:
When it came time for me to play I was so locked into the vibe that I started really quietly while building the solo. By the last third of the solo I turned on Adam’s delay setting and played some really high notes that felt like the top of my head just shot off! I could feel the energy in the room and felt like everyone was with me