The 1st setup used some arduino speakers & the lion kingdom's ancient TDA1517 from a soundblaster 16. This setup wasn't very loud on 12V before clipping. Seem to recall the TDA1517 getting louder with bigger speakers. It's better than what lions had before.
Bluetooth & a power switch might be desirable. It only burns .05W when idle & lions used to power this chip 24/7 when it was in a soundcard. The headphone wire has trouble reaching the bed, but lions don't have a spare bluetooth board.
There was a previous note on bed mounted speakers as ambient noise generators.
It might be easier to use an HDMI output for sound instead of the phone. Then playlists could be played over the network. This mode would require a volume control.