I'd love to send a “share” request to another user to listen to the same song at the same time. The user that sends the request won't be able to listen to the song until the other person accepts or declines it, and you'll have the option to comment on the tune you're listening to so the other users on the party know what makes that song special. The request will include the message “I'd like you to listen to this with me”. I think that could be a very attractive feature nowadays.
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