Michael, did not realize that your ceiling slanted back so dramatically. That may well save the day - but I would still begin with speakers in that situation. Magnepans might be very good indeed - I have run them on everything from '70's mid-fi 100WPC to modern hifi high power, and have always liked the sound. My Quads are more sensitive to amplifiers, but Quads might not work with your room.
Experiment! Good luck!
Experiment! Good luck!