Thank-you.
The notes I found online suggested:
GGDDEED CCBBAAG... And so on.
As this was the last achievement for me to get platinum (for the 0.9 update, anyway), this has been frustrating me for a while, and I'm ashamed that I never considered simply starting on a higher note.
Thanks again.
Now I just need to play around and find the last 2 unlockable songs.
In your honour, I'm naming my character "Scylla" for the next playthrough.