:agree::agree:
Lot's of good suggestions here. Someone may have spoken to this already.
Forgive me if it's a repeat.
My advice is contrary to others, and contrary to what you've asked.
I've found the best music comes from in-helmet speakers.
The newer systems can be set up with battery operated bluetooth so you don't have to deal with installation or wires, and you have the added benefit of an intercom between you and your daughter.
You can use a smartphone or any bluetooth mp3 player/radio for a music source that doesn't take up a lot of space.
Also counter-intuitive, but you get better sound if you wear foam earplugs. The earplugs will cut down the extraneous sounds, but your ears are close enough to the speakers to allow the music to get through.
As always, my free advice comes with a double your money back guarantee.