20w amplifier for iPod

[selwonk]

Can anybody suggest any sites or shops that might be able to sell me a 20w mini amplifier? I've got some 20w non-powered garden speakers which I'd like to run from the iPod headphone socket (it's docked and the dock has no line out). I've found this on eBay:

http://cgi.ebay.co.uk/20W-Hi-Fi-USB-Audio-Stereo-A...

Would that do the job? If so, I'd like to get hold of one before the weekend. I can't find anywhere that sells them over here. Any advice much appreciated.

Thanks in advance.