I need a adapter for the pro speakers of an old iMac PPC. I would like to use them with an Mac Book Pro. Where can i get one?

The only adaptor--the Griffin iFire-- that would allow you to use those on another Mac model have been discontinued for some time and now go for so much money that you could buy an amazing pro-grade speaker system for the same money:

http://www.amazon.com/Griffin-iFire-Amplifier-Adapter-iPod/dp/B00013MRT8/ref=sr_ 1_cc_1?s=aps&ie=UTF8&qid=1384613876&sr=1-1-catcorr&keywords=ifire

IMHO, not worth the cost or effort considering the excellent selection of modern external speakers we have now.

I have a set too and they are in the box, currently unused because we've upgraded past the G4s that used them.