I know there is a lot of debate about if speakers do sound better after proper break-in time. If you are a believer, or even if you arent but know all about it, what would you recommend as good break-in audio?

What types of music would you listen to or leave playing on repeat? I tried to google it and couldnt find anything! I probably could have done a better search. Is it something i can find easily?

Thanks in advance audio smarties!!