Other then the fact that somebody might claim that that's not music at all (even during the rest of the year), this is 100% the same as taking a synthesizer and playing music.
I am pretty sure I agree with you. The only thing that makes me not sure is a psak I know of (from personal involvement) of a woman who wanted to make a recording of a song she had written. The recording was going to be given to a man to hear the sng and decide whether or not to use it in his own professional singing career. They asked a shailoh about how she could have him hear her song. The psak was to record it and then use a synthesizer to adjust the voice and then it wouldnt be kol isha.
Kinda like wearing a Sheitel. :)