King Crimson Live in Chicago: Lizard Suite; The Construkction of Light; Pictures of a City.
that's three, (of a perfect pair) from one live album. The musicianship is out of this world and the recording is tight.
Would love to throw in some Zappa, Watermelon in Easter Hay is fantastic off Joe's Garage.
Also some of the newer Rush recordings off Counterparts like "Leave that thing Alone" - super test for your equipment.