Very cool. I really like it. The one concern I have is how similar the mark looks to the "beats" by dre. Try doing the same one but with the entire b inside.
Can you do #379 the same with the only difference to the "b" that you give a slight space between the "b" and the edge of the circle? making the top of the "b" end inside of the circle but instead of strait across, have it follow the curve of the circle.