Yeah, this guy is an absolute freak. He hasn't practised the piano in years (he doesn't even own one), but when he does play he can sit down and play practically anything. My twin, older brother, dad and i have cobbled together our own string quartet, and he sightread through the brahms piano quintet, trout quintet, schumann quintet and mozart g minor quartet, never having even heard half of them.
I've got a recording back in england of us doing the first brahms clarinet sonata actually. When i go back i might try to dig it out and post it up.