He's possibly one of my favourite villain concepts ever. A sort of Dr. Phibes-ish character, with a dash of Moriarty thrown in perhaps?
A famous concert pianist who gets fired, and has his revenge by writing the 'symphony of death', which kills anyone who plays it, and mailing it to his ex-employers.
I can't help but imagine him going further and further. Writing jingles with a hidden frequence or pitch in them which causes instant death? Ring tones? Pop songs? Imagine the damage this guy could do. I see him assuming a series of alternate identities and making his way through the music industry, leaving a wake of carefully concealed destruction behind him. A worthy addition to this evil, evil team.
As to visual changes, I gave him a bit more hair and I took away the skull tattoo on his forehead, and substituted it with a suggestive group of moles.