Check the www.klipsch.com forums. You will find that McIntosh gear works quite well with the vintage Klipsch, and in fact we just purchased an MC7200 (200W SS amp) to go with our Klipschorns. It sounds like the other end of the sonic spectrum--as it should--from the 4W SET amps we also use, but both are incredibly rewarding, and a good match for the speakers. Be advised that the La Scala's are actually rated to 53Hz (not 35). Consequently, if you want to fill out the bottom frequencies, count on getting a sub. We used an ACI Titan, and it blended in with the La Scala's so well that not a single listener ever suspected it was on. In my opinion, the modifications to the La Scala--damping the horns with Dynamat, re-wiring with silver, and upgrading to new crossovers--are essential in getting the most out of these speakers.
Best of luck!
Best of luck!