Prevent iTunes from opening when connecting bluetooth speaker

I did read iTunes keeps starting automatically but since I don't have the console output mentioned in this thread I don't know how to pin down the problem. So iTunes keeps opening when connecting my speaker (UE Boom) via Bluetooth. I did read that iTunesHelper could cause this. So I quit the process in Activity Monitor, removed it from the login items and renamed the application as suggested in iTunes Helper still running even if it is off. But iTunes still keeps starting, iTunesHelper doesn't it seems as I cannot see it in Activity Monitor anymore. I am running Mavericks 10.9.5 and have iTunes 12.1.0.50 installed. What can I do to prevent iTunes from starting automatically?