Conversation so far:
Is La Monte Young still actively making music?
CANNOTANSWER.
Have any albums been released since 1970?
In 1974, the two released Dream House.
Who is the other person in the "two"?
Zazeela.
Is Zazeela a relative?
CANNOTANSWER.

Question: How long has he partnered with Zazeela?
Self-contained rewrite: How long has La Monte Young partnered with Zazeela?