Good Audio Dealer in San Francisco

I used to live in the SF Bay Area, but I didn't frequent SF itself. If you're willing to drive down to San Jose, I highly recommend The Analog Room, on Fruitdale Ave in San Jose. They carry ProAc. They also carry Sonus Faber, which I'd offer as an alternative suggestion.

I would highly recommend both the analog room (they don't carry Sonus Faber but do carry proac and others...you can find Sonus Faber at Bay Area audio) as well as Saint Celia's. Saint Celia's carries Alon and I believe JM Reynaud and perhaps 3M. St. Celias is also outside of SF but an easy 30 minute drive.
Righin SF is San Fran stereo which sells B&W, Dynaudio as well as others.

I second the recommendation of St. Cecilia Sound Gallery in Heyward (http://www.scsoundgallery.com/). Brian, the owner, sells a fine selection of monitors, including the Reference 3A De Capo, Soliloquy, and Alon. The last time I was there, he had a pair of Silverline SR17s on sale, and I admit that I am partial to Silverline (I have Sonatinas myself).

Also over the bridge from SF is Music Lover's in Berkeley. They have Joseph Audio, Revel, and others.