Speaker Choice ?

I had dunlavy sc III's in a room a little smaller than that and I agree 100 percent that dunlavy 4,5, or 6's should work extremely well in your room.
I ran tube amps with mine as well; audiovalve challenger 180 monoblocks and the sound was stunning; my only complaint was the bass could have been better but I always thought that was related to the sc III's having only 8 inch drivers; the 4,5,or 6's have larger woofers and should pressurize the room even better. Dunlavy's are still a tough speaker to beat with even todays makes.
Also now and then Duntech speakers show up in the used market and should be considered as well; I know they are similar to dunlavy but I do not know how the link is established.

Reference 3a Grand Veena (used) VAC 160i.

see if Vandersteen's voice is something you might like.

03-05-15: Zimwig
Reference 3a Grand Veena (used) VAC 160i.

That's the exact combo that I'm rolling with, sounds great!!

You guys may have a laugh at this, but in my 2-channel reference room I'm using the Dunlavy SC-Vs with a Dunlavy subwoofer. Only a few of the subs were made and this one is in an SC-IV cabinet with 4 twelve inch woofers. It's passive so I use a separate amp/equalizer with it. The result, well if you love your bass clean and able to slam you through the floor, this set-up gets it done.

Also, I agree with the recommendations for tube amps. I've tried different amps, but personally I have liked the high current stuff from Jeff Rowland and the Marantz Reference Monos the best.