Does an adapter exist to make USB speakers convert to standard 3.5mm jack?

I bought the Harman Kardon Soundsticks (I not II) back in 2002. I have loved them for their great quality but I recently saw that Soundsticks II feature a standard 3.5mm audio jack as the output instead of a USB output like mine has. I would love to use these speakers for my stereo and tv and ipod, but I have googled away and all that ever comes up is 3.5mm to USB converters, and I need the opposite. I hope this question makes sense, If you have heard of such a thing maybe just tell me which site might have it or at least what such a converter would be called. It seems a shame to replace such perfectly good $250 speakers. Thanks in advance