Whats a great amp for Sonus Faber Concerto?

Hi guys,
I bought these speaker used about a year ago, i know they are pretty old. I dont believe i'm doing them justice with the receiver i have them connected to. I'm looking for an integrated amplifier. Which ones do you recommend? I would like to spend $500-$1000. Any amps (new or used) in that price range that would work wonderfully with these speakers?