Welcome to Head-Fi and sorry for your wallet!
Oh, and there are many topics here that are very hard to miss about great matching amps for the HD650's. Not hard to find at all! Just search around and you should find your gem! Oh, and you have to determine how much you're willing to spend. IMO, a budget of about $300 or more can start you off real good with your HD650's and I don't really recommend using portable gear with it (some may disagree but that's how I feel).