King Crimson - Improv: ZoomZoom
Ow. This has to be the least AMVable and most pretentious thing to post here. i) It's from a rare collectible official CD sourced from an unauthorized recording of the first ever outing by the band's most legendary lineup in Germany, 1972. ii) It's completely improvised iii) it's 44 minutes long and, on top of that, preceded by another 22 minute improv.
What to say? All I can say is that this has just been the most fun and fulfilling music experience I've had in the last 3 months or so

Back then, in 1972, it was music that noone else had ever heard or even dreamed of. Today, it still sounded brand new - maybe not surprising, since in the last almost-32 years, nothing like it had ever appeared again
