Very nice -- can you return the orange color to the "e" and the "theory"? It also seems to me like the G-clef is leaning a little to the right.
Then it's mostly up to whether we go with the simple & clean design like this, or something like brad2's design.
I really like there to be some kind of visual thing that's subtle, but someone will notice and say "hey, that's cool"... but I don't know much about creating that kind of effect. Currently the leading logo has a graphic that I love but the overall logo is not feeling "together" enough.
Thank you for your submissions, and I welcome any advice!