If you want good sound late at night you can't beat a good set of headphones. That being said the cornerhorns will sound good without a lot of watts. I didn't really like the distortion in the Delta 15 speakers when I had them. (they're in a box in the basement now.)
I have a 3 way cornerhorn which uses a high efficiency mid in a non-horn setup. The imaging is good with this set up. The 4 Pi guys also claim good imaging with low watt systems.
Grant.