Definitely read the Klipsch Forum's as Jwc37 suggests. You can read my comments on MY experience and opinion of the ALK on my LaScala's by reading my comments on my Virtual System. In a nutshell, I prefer the Klipsch AA's, but if you like a cleaner focus at an expense of soundstage width and depth go for the AlK. YMMV though and it is well worth getting more input. I think it is pretty unusual to find that any of the Klipsch heritage products fall short in the midrange. Are you sure all your horns are working properly and that you have not blown out a diaphragm, or have a bad crossover, bad oilcap, loose wire, etc.......have you gone through everything on the Cornwalls? If you pointed to one of the extremes (high's or lows) I would not be as surprised, but the Klipsch Heritage speakers are midrange champs, especially with tubes. You start out by saying it's the mids that are lacking and later on mention the "top end". Which is it? Are your Macs tube or SS? If they are SS, well then, my truly jaded opinion is that you are wasting a pair of good horns. I have only heard these speakers sound harsh with SS amplification. With tubes they are heavenly to my ears. If it's the mids you are lacking in, I would check those drivers, crossovers and connections and make sure that's all working before taking more expensive actions.
Marco
Marco