Little known is tricky, but I thought through my list of recordings that define jazz to me, perhaps one you may not have heard? You can skip the last one :-)
Armstrong - Hot 5 and 7
Blanton Webster band- Ellington
Love Supreme - Coltrane
Ahmad’s Blues - Ahmad Jamal
Quintet live at Massey Hall
Koln Concert - Keith Jarrett
Monks Music - Thelonious Monk
Miles - Nefertiti
Jimmy Guiffre 3
Miles- Kind of Blue