I'm 65 now, but I first went to Manny's (my mom took me) to buy a Ludwig drum set at the age of around 10, around 1965.
This was the original Manny's and Manny himself helped me pick the black lacquer set.
Manny's wasn't the amazing palace of instruments it became; it was a modest narrow shop.
When I switched to electric bass at the age of around 14, I returned to Manny's for a Gibson Les Paul bass and I forget which amp.
My younger brother bought a red Hagstrom guitar there (our father took him) on a sunny Saturday morning around 1967.
I played the Danelectro bass many times there; my brother played the 6 string.
I remember my brother trying out a fuzz box pedal.
While I don't recall seeing anyone famous there, I always knew that this was THE place to be.
And yes, while Manny (and later his son Stu) were very patient with me always, there were limits: Don't play too loud or too long....AND DON'T PLAY STAIRWAY TO HEAVEN.
I miss the entire Manny's experience and always will.