Hello! Weekend is still far away, but there it is, I managed to put the high-pass filter into the music box, and added note-damping when the note is stopped. Unfortunately, the clicking noise is still heard, but now it has become a very short crackle instead of the click which still can be heard all over the song. 

The crackle is mildy audible and it becomes very prominent when it has fast note passages, which could sound irritating. The good news is, half of the clicking has been gotten rid of because I damp the notes right after the note-stop event.

There is still some more work to do on it, and I'll post up a Youtube of the thing playing music soon! Waiting for that weekend now... :)