I don't recognise those in your avatar and signature, but it does look nicely composed and they match up well.
Avatar: 6/10 - It looks a bit grainy, and the characters would look better if they taken up more of the avatar. Nice delicate use of grey.
Signature: 8/10 - A lot more better quality thatn the avatar, seems very clear. Very simplistic but works very nicely and the background colour isn't too over-whelming. I like signatures with a bit more "happening" if you include characters, it's just four guys and a post.
Overall: 7/10 - Balancing out, it does look rather nice with each other, nothing too extreme to the eye. Maybe if the avatar could've been a bit better I would consider rating it an 8/10 at most, but I'll stick with what I've given. Nice!