Grayfolded: Transitive Axis (1994)
For those of you partaking in item #1 -- of just looking for some trippy instrumental background music for your work-at-home duties -- I give you Grayfolded: Transitive Axis (and its sequel from the following year, Mirror Ashes). And while this is largely of interest to Grateful Dead fans, I posit that one doesn't need to be into the Dead to appreciate this.
Long before mash-ups there was "Plunderphonics," musical collages created by Canadian composer John Oswald. For this project, apparently at the request of Dead bassist Phil Lesh, Oswald created several musical pieces crafted largely from bits and pieces of live "Dark Star" performances over the years. As "Dark Star" served as the band's primary stepping-off point for extended jams for decades, he had plenty of material to work with, stitching and looping segments on top of each other.
Dead fanatics can occupy their time trying to identify the eras or even particular shows -- spotting a '69 jam overlapping with a '90s performance -- while novices can just enjoy immersing themselves in the sonic pastiches. Although a few hours of jams built out of the same song may threaten redundancy, there is still plenty of variety, not just in tone and ambience as he moves around the decades, but in musicality. Some of the songs are based around the actual "Dark Star" song structure, others just sort of meander into the deeper spaces. A few times he leaves "Dark Star" itself behind, such as on "La Estrella Obscura," built out of various takes on "Spanish Jam," an instrumental passage that the Dead would vamp on either as part of "Dark Star" or leading into and out of other songs; on the second set of music, "Cease Tone Beam" focuses on intertwining feedback (ok, not everybody's cup of tea, though still a bit more palatable than Lou Reed's Metal Machine Music), while "Dark Matter Problem" introduces elements from "The Other One."
It's great with headphones and some herbal indulgence, or just drifting around in the background... whichever way your pleasure tends.
Here's a sample (with a timeline showing the musical sources, if you're into that sort of thing):