I discovered this fact earlier this year when I was in NYC - like a ghost town for music gear. I used to work five minutes away in the early '00's - spent many lunch hours lusting over the basses at Manny's, Sam Ash, Rudy's. And the amps were ridiculous.Yes, in fact no music stores on 48th st anymore.
Only thing I found equivalent was Denmark Street in Soho, London. Went to Wunjo Bass - absolutely packed full of basses. I was nervous to turn around. The whole street is music stores. Great place to spend way too much time (and money)!