My room is of similar size (16' X 34' w/cathedral ceilings), and my custom built 12" Tannoy HPD's, are able to fill this large room to very good effect with as little as 9 Wpc (SET 300B), but they have also sounded extremely good with 300 Wpc of solid state amplification.
You might consider investigating Tannoy.
Regards,
Dan
You might consider investigating Tannoy.
Regards,
Dan