Like Topspeed said, efficiency is a killer with those old speakers. You'll need to match that volume (and sound) to pull it off. The old school pro-audio type drivers are simply LOUD. Modern woofers are different animals and cannot keep up. Heresy uses a 12.00 and are the weakest of the old Klipsch. The 15.00's in the Cornwall are considerably louder. I was able to get close with two 8.00 relatively high-efficiency woofers (Dayton Series II) in parallel, my target was 96 dB. Pro drivers on the market are typically 12.00's, perhaps 10.00's, I did not have the room.

Get it right, the sound is great.

You'll still want a sub for home theatre, IMO.

jocko