Big Below 15k used that can play loud as heck

@danager+1, the Altec VOTT will do the job and do it beautifully.  Although it uses a 15"/16" driver it does benefit from well integrated subs. You will probably find it with the 511 horn for the high range. Remember they were used for cinema and can crank like crazy while still sounding great. You may need to reinforce the cabinets and damp the alloy horn but the extra work is well worth it. Check to see that the cab is loaded with the Altec 416 woofer and that it is not sporting some cheap replacement rubbish. All parts still available from GPA

If you want horn and supper efficient (103db measured), and can find one used these should do 

Zero1-xd

 Zero TA

I have the bigger brothers and are absolutely amazing.

I know that they are not popular in the USA but well worth the search. 

Legacy Focus SE

JBL M2’s

Tekton

Ohm 5000’s, or their F5’s (or the predecessors to the F5’s)

I thought I responded to this discussion already and if so, I apologize. Volti Audio Rivals are just about as efficient as any Klipsch, will play VERY loud with maybe 20 watts  and sound better than any of them. The hand built quality of construction, crossover components and drivers are also  superior to them. Look great, sound great ( big, open, dynamic but also detailed)  and not crazy large. Contact Greg Roberts in TN, he’s the owner, designer and builder and would be happy to talk with you.