less than 100 pounds I reckon!
I imagine I could pick up something like this (second hand) for that price:
Pioneer A-209R Stereo Amplifier - Black: Amazon.co.uk: Electronics & Photo
All i really need is a left and right line in (as I play my music from my PC) and a phono connection for a record player.
I can't seem to find anything on the specs of my speakers I'm afraid.
Cheers