We have made contact with a professor in the University of Texas library system, which has a 200,000 record archive of popular music recordings. They are kept under museum conditions in a climate/humidity controlled building on the UT Austin campus, and digital copies are made of each recording so they are available to academics.
They lack death metal and black metal, but they keep any other kind of underground, ethnic, mainstream or classical music. They need you to send them original recordings of death metal and black metal, especially rarities which will be kept in perpetuity in a safe environment.
I think this is worthy. If you’re serious about what you say/sing/play, it’s worth having others try to understand it in context. Hopefully someone has already hit them with a wad of The Wild Rag and maybe a copy of Until the Light Takes Us or Glorious Times.