I have a 6yr old and 8yr old, both would love to have a music player for Christmas. We have Spotify, I'd prefer to use this than get a cd player/cds, but have no idea how Alexa/echo dot etc work. They don't have their own tablets/computers, but would like to play music in their rooms. Do either of these work in this way? Do I need extra subscriptions etc? Totally clueless here, thanks for advice!