The speaker set is only very modest and i'll only be using it when the bike is running. I know a guy that runs a small power-amp off a 50cc scooter (i think its a yammy aerox) so power in my case should be fine.
As I commute to work locally on a relitavely quiet road, and my bikes engine pretty much whispers so volume isnt too much of a demand, plus, the speakers are directional and were designed for motorbikes. I know my music will be heard by fellow commuters but to be honest I can hear every second cars radio anyway, and I wont be trying to blast anyone away.
I know what you mean with the bluetooth headset/earphones, but i've been avoiding them as I feel I wont hear the road if music is pumped directly into my ears.
Thanks for your help so far