http://www.dremeljunkie.com/2013/01/imac-g4-ivy-bridge-hackintosh-finishing.html said:
With the exception of some cosmetics, I have completed the back ports. They include 4 USBs, though 1 is used by a small Bluetooth adapter, a 3.5mm audio jack, the native AC power plug, and a "fake" Firewire 400 plug. Its fake because it isn't a true firewire cable, it is only connected to a 12V Molex/Ground, so it supplies only power. This is for use with the Griffin ifire adapter which gets its power from firwire and its signal from a 3.5mm audio jack and has an apple minijack out for the apple pro speakers. This is very much akin to the original apple pro speakers that came with the G4 Cube. They used an external amp which plugged into a special "high voltage USB port". So although the speakers are not directly plugged in like the original, with the iFire, no additional power source is needed. I did not want to break open and try to internalize the iFire. This would have wasted the valuable iFire and constrained this mod to only those speakers. The iFire also allows lengthening of the speaker cable, which is far to short on the apple pro speakers.