Conversation so far:
Is La Monte Young still actively making music?
La Monte Young  musical career has been active 1958 through present.
Has La Monte Young released any albums since 1970?
In 1974, the two released Dream House 78' 17.
Who is the other person besides La Monte Young in the two releasing Dream House 78' 17?
The other person in the two is Marian Zazeela
Is Marian Zazeela a relative of La Monte Young?
Zazeela is Young's spouse

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