I looked up your model http://www.everymac.com/systems/apple/powermac_g4/ports/powermac_g4_qs_2002.html According to this, speakers like the ones you have should be in the headphones jack. An "Audio In' Jack is for digitizing and recording analog audio like from a cassette deck or mixer. Again according to what I read, your computer should have a speaker jack that will only take a particular jack that is attached to Apple Pro speakers http://www.synaptech.com/catalog/index.php?main_page=product_info&products_id=441¤cy=USD Which are matched to the whole deal and are very pleasant. I have a pair on my 2001 QS . 6+1/2 years old, still working. Jim On Jun 11, 2008, at 4:58 PM, Bill Disney wrote: > I'm new to the group and recently bought a Apple G4 Dual 1GHz > (Quicksilver 2002) (M8667LL/A). At the moment I have CA (cheap) > audio speakers plugged in the rear Headphone jack. Is there a > special adapter that can be used on the 1/8'' speaker jack to plug > into the Audio in jack on back of G4? Would the sound quality and/or > volume be enhanced? Should I not be using the rear Headphone jack to > run any speakers but only the Audio in jack? Any suggestions > appreciated - thanks.~Bill > > > > _______________________________________________ > G4 mailing list > G4 at listserver.themacintoshguy.com > http://listserver.themacintoshguy.com/mailman/listinfo/g4