as to classics you NEED to listen to. I don’t like many classics but I’ll offer a few that others may not:

Mr. Bungle - Disco Volante (seriously.. and if you survive it, try their other two albums. the first album was very influencial on nu-metal while being not-at-all nu-metal)

Aphex Twin - Richard D. James Album (and everything else, but that’s a good start, along with the ’Come to Daddy’ EP)

King Crimson - Larks’ Tongues in Aspic (for the instrumentals and beginning of them being one of the most influencial prog bands, especially on the metal side)

DJ Shadow - Endtroducing (total classic of instrumental hip-hop)

… I suck at ”classics” unless we’re talling weird stuff that probably goes nowhere near your tastes.. all else I can think of that may fit is Björk but you’re already into it (she’s a good one to web out from in ways I suggested above, having worked with sooooo many people, from Mike Patton to Bogdan Raczynski to etcetc)