Welcome to head-fi, natelam!
Before you settle on the 650s (which are one of my favorite headphones) and the airhead (an adequate first amp) you might want to do some more research into what the 650s really need in terms of amplification. They weren't really made for portability, and really require a more powerful amp than ones such the airhead. There are some portable/transportable amps that are better than others, and some are dang nice, but none, imo, are great with the 650s. Though you can enjoy the 650 sound, they really sound best with home amp. There are also some excellent sounding headphones available that aren't as hard to drive as the Senns, so you might want to look into that as well.
Although I'm personally prejudiced against the 650s and portable amps, I also understand that this pairing may be what's best for you at this time. If you're set on both a portable amp and the 650s, I suggest checking out a mini^3 from Rockhopper Audio, and choose the higher gain option. It runs about $125 and will do a better job than most, if not all, in that price range.
Good luck!