@sgunhouse , What tab? I just open Opera and the music starts?

So, you're saying that with just the speed dial tab open, Opera plays music on startup?

Do you see the speaker icon on the left of the speed dial tab in the tab bar? If so, maybe it's one of your dials that's somehow playing, I would assume Opera disables that, but maybe there are certain circumstances when that works.

Maybe it's one of your extensions?

Go into the properties of the shortcut you use to launch Opera and look at the command on the Target tab. Maybe it's set to launch a certain music file where it's not showing up in a new tab for some reason.