Wow! That's an awesome pick up price on those AR-9's. If only I could find a deal like that.
As to amps, the Adcom amps that you're already using are often mentioned as being a good match for AR speakers. But, there's a lot of vintage amps that should work too, one being the classic war horse, the Hafler DH-500. Also, off the top of my head; Carver; M-1.5t, TFM-35, TFM-45, and Sunfire Signatures. SAE and Soundcraftsmen had some nice sounding big amps. The Sumo Andromeda. Yamaha has some very good high power amps with high damping factor, MX-1000, M-2, M-80, M-85. I'd look for Acurus A250, or Aragon 4004 and 8008 amps too. Parasound, HCA-2200, or one of the new Parasound Halo amps. Also new, Emotiva has a cult following for their mono and high power stereo amps (internet direct only). Even look at pro amps. The Crown XLS amps get very good reviews, and output very high power into 4 and 2 ohm loads. And they're cheap too. Other than those, you can always go Krell or Threshold or McIntosh!
Good Luck!
