Yeah, Cream (they were in NYC recording Disrali Gears) opened for the Who at that Murray the K Easter Show. About eight acts performed around five shows a day between showings of an awful black and white Brittish film. The groups did one or two songs each.
Cream always played I'm So Glad and I Feel Free. Then the Who would come on and do Happy Jack and My Generation. I stayed for several shows. This was the real thing. Mitch Ryder's band opened and so did Wilson Picket.
This all took place a few months before Monterey Pop.