Speaker / Amplifier for headphone output?

I've posted several questions with respect to the possibility of connecting a MIO 268 to a radio-mute type connection to the car radio but no-one's come up with any solution (although I'm still sure that there is a way with this unit!!). My "next" thought would be to connect the headphone output socket to some form of amplifier / speaker (the kind that they used to sell for the Sony Walkmans to be able to listen to them without headphones) and was just wondering if www.totalpda.co.uk knew about (or even sold) them. I'm sure that they wouldn't be that expensive but it would resolve the "lack" of power that the small GPS units have - at least whilst I'm listening to music at the volume I like!!!

Looking forward to any suggestions,

Thanks,

Raymond

I've got a small powered walkman powered pair of speakers which run off 4 AA batteries, works a treat, cost £9.99.