i recently bought an iMac G4 in almost perfect condition. The Apple pro speakers are in great condition and work fine whilst the Mac is booting up. However, after bootup, no sound comes through them. I have tried altering the computer's audio/midi settings, restarting the computer and played around with the sound settings. The only option listed is built in speakers. Can anyone help? I'm told these speakers are really cool and I would love to get them working again. Thanks in advance!