Streamus

If you prefer playing music in the background, Streamus is for you. The addon brings a YouTube music player into your Chrome that streams your favorite music without you having to open YouTube in a separate tab.

The big advantage is that you manage YouTube from your current tab and it only streams the audio while the video stays hidden. There’s no need to have multiple tabs open for music.

With Streamus, you can search YouTube videos in a little pop-up window and add them to your playlist. Or you can turn on the radio mode and let the extension find related music based on your existing playlist.

Streamus lets you save songs / videos in playlists that also get synched with your other computer where you are signed in with the same Google account.