Yes, you can stream music to a bluetooth device (like my Resound Phone Clip+) or in some cases directly from an iphone. The music would be stored on and played from your phone, tablet, laptop, or one version of the old ipod had bluetooth.
One benefit of streaming to your hearing aids is that the sound is “tuned” specifically for your hearing loss.
Research Phone Clip+, ComPilot II, ComPilot Air, Smart Connect, Com-DEX to get an idea of how they work.
You can have your hearing aids microphones stay on during streaming, if you want, so if someone talks to you during streaming you might be able to hear it, or if you pause the music the microphones are on and they could repeat it.