I actually have an old Sony portable CD player, I should dig it out and see what voltage it needs. I could plug it into the same speaker I run off of my tablet for MP3s...but I am trying to get away from carrying a bunch of CDs on the trail.
Altec Lansing iM227 Orbit $20.00 - Single speaker (not stereo), extremely small and light, 24hr battery life (3 AASs), carrying case, very limited sound quality and volume.
What is the best outdoor music system??