I concur with the Parasound suggestion, but if the A21/23 are a little high, you could go with their Classic line. Used the 5250 would be under your limit, and new Audio Advisor still has some(no affiliation!)
Another option would be a Nad 275 used, they put out 150 wpc, which is plenty for your Klipsch.
Another option would be a Nad 275 used, they put out 150 wpc, which is plenty for your Klipsch.