The NAD S200 is a wonderful amp but as mentioned, you really don't "need" 225w/ch to drive a pair of HIII's to crazy levels. If you are not quite ready for tubes but still want a "warmish" sounding amp(mosfet) that will mate very well with Klipsch Heritage, look for a lower power(125w to 140W) B&K like the Reference 125.2 or the ST2140. Both are very nice sounding amps with Heresy's and are reasonably priced on the used market.
Any of these NAD integrateds will sound great(IMO) with the Klipsch Heresy's also.
http://app.audiogon.com/listings/solid-state-nad-c352-stereo-integrated-amplifier-like-new-2012-09-17-integrateds-34233
http://app.audiogon.com/listings/solid-state-nad-c356bee-integrated-amplifier-with-warranty-and-free-shipping-2012-08-22-integrateds-01060
Bill