Mce: KEEP those horns! I'd take 'em in a heartbeat if I had corners, but I don't so that's why I've stuck with my classic Belles (same drivers & x-over as Khorns but in a beautifully woodworked box cabinet) for >20 years. I like mine with about 200 watts/ch of *quality* solid state amp (presently running Accuphase) which barely strains much over 5 watts on the output meters. All the rest is for headroom, which compliments those great horn dynamics wonderfully.
If you want better sound then now is the time to look at cabling upgrades: MIT MH750 speaker cables synergize very well with this combo (I now have the Magnum BiWire version after upgrading from older MH750+). Synergistic Research interconnects & upgrade AC cords are your next step in the right direction. Spike those speaker cabinets too (I liked the BBC MK2 gold plated brass cones). You can even install some upgrade ALK crosovers & a *bunch* of other tweaks to make your already great speakers even better (see the Klipsch website bulletin board under "upgrading older speakers"). Perhaps some some better equipment too, but realize that the Hafler matches up so nice with your Klipsch because Halfer has mosfet outputs. Of all the amps I've tried with my Belles, mosfet's always worked the best. Some models of Perreaux & Classe would be worth trying, or the Ayre V3 is *very* nice too (email me for details regarding a good deal on that one - hint). I've always had noise problems when running tubes w/Klipsch because they're so darned sensitive - any little tube rush noises, microphonics, oscillations etc. were just awful even with a tube pre & SS pwr.amp. The only tube pre I ever liked was a very quiet Golden Tube SEP-2 or SEP-3.
What other speaker can give you those great horn dynamics & also work well without being placed all the way out in the room? I just don't know - there may not be anything else? Lowthers I've read about but the bass is reportedly compromised. Avantgardes yes, but they're crazy expensive compared to what you have & also look even more unconventional than what you have (wife might *really* cringe) plus I don't know if they even work at all when placed up close to walls?
Whatever you do, don't listen to the wife; she just doesn't know what you have there! Speakers are about SOUND, not necessarily architecture / interior deco. Don't do something that you'll absolutely regret for the rest of your life!