Wow. My office is 6' 4" by 9'3" so I get your situation completely. For a vintage look, the LS3/5A is your winner. It is designed as a nearfield monitor, where none of the other speakers mentioned had that as a consideration. The Infinity's are too 'modern', the Wharfedale's are too big, and the Heresy's are WAYYY TOO BIG. If you're really a Klipsch fan, consider the RP-400 or RP-500. Also, Acoustical treatment in a small room is crucial. Get about 6 or 8 24" square or 12" X 24" rectangular 2" panels for you walls and ceiling, They will make remarkable difference by controlling the early reflections. Acoustimac made mine, and I am thrilled. I use them in my lots-of-glass living room, where they help more than the sound system, I use them in my theatre, along with bass traps. And I will use them in my office shortly. Good service, good price, good selection.
I'll stay out of the amp discussion for now other than to say you won't need much, but it must be cleqn. The LS3/5A's are sealed, so having a subsonic filter isn't a big deal, but the Klipsch are, so being in close proximity to you turntable, a 20Hz high-pass subsonic filter will be a must. Woofer flap is not good for the speaker or the SQ. And as much fun as a tube amp would be, that's a small room and it could get very stuffy very fast from tube heat.