The best speaker for a small room...at any price point.

Because you are talking about such options as stacked Quads, I take it you are not limiting your selection to tiny speakers for the tiny room.  One of the better stacked quad setup I heard, that comes with an active crossover and dedicated EL34 amps for biamplification, is assembled by a firm named Emia.  The system is big, and can play at shockingly high volume level, and I liked what I heard in a tiny hotel room at a show.  It is not a Quad with more volume capability, so, you do have to hear it even if you generally like the sound of Quads.

The recommendation of Charney speakers is dead on.  They are amazing sounding, and work with the very low-powered tube amps which are the type of amplification I prefer (they are over 100 db/w efficient).  The model I particularly liked had the AER driver and cost something like $18k.  It is a plus that their systems are relatively compact.

You could also be a candidate for custom-made speakers.  Look up Deja Vu West (San Diego).  It is a store affiliated with Deja Vu Audio (Northern Virginia) that builds its own speakers out of vintage and new drivers.  Most of their systems are particularly suited for smaller rooms and can be tailored to match your circumstances.  The price range for custom systems is very broad, but most are in the $30k to $80k range.  

I also encourage you to add  the Joseph Audio Pulsars to your  audition list. I heard them at "The
Show" in Oakland CA last year. I was mightily impressed!

If you like pulsars, go call lsa..underwood hi fi. LSA bookshelves are as good as pulsars, much lower price!!!!

I have Aerial 5T's and they are excellent in my apartment. They were mentioned earlier.

I don't know if you would want to be locked into a particular manufacturer's products but I think the Steinway Lyngdorf line of speakers like the model S or O are spectacular in both sound and looks.  Only problem is that you would need to use their amps exclusively AFAIK.

Room perfect is the real deal in room correction and placement of the speakers wouldn't be an issue.