Hi-Fi Fo Fum (cool name, eh?). There are two locations, the one I used to go to is on Big Bend, about a block from Clatyon Road. There is another place called Best Sound on Lindbergh, which I used to visit as well. They're both decent shops.
While not a conventional stereo shop, I'd suggest you contact John Hillig at Musical Concepts/Musical Design: http://musicaldesign.com/
They typically service and carefully modify varieties of noteworthy equipment for the high end crowd and know a great deal about what makes valuable audio sense. They may even have new or used gear on hand, but a call or visit to them would not be a bad idea. Good luck.