I prefare to busk just accoustic with the harp, however, after 2 or 3 hours of playing, my fingers look like Pigs Tit's!!!!!! And I can't play for a week! An amp stops all this, BUT you have to keep moving on, just for the shopkeepers, they dont mind so much when you return. (everything in moderation) Anyhow back to the point- Alison, go for an amp that is powered by 12v motorbike battery. You can re-charge the battery: An amp that is powerd by 12v is much more clear, (Plenty of amps!) BUT- its not about high volume, just clear audio to the same level as say a good guitar/ whisle etc. John the harp; or Pigs Tit's, if you prefare!