PowerBook: Audio Play Through Support

I am trying to connect a Walkman to the Sound In port and have the sound play through the PowerBook 5300 speaker but it is not working. What PowerBook models support audio play through via the Sound In port?
Because of hardware architecture, routing external audio through the line in (Sound In port) option is only supported on PCI PowerBook computers such as the PowerBook 2400, 3400, and PowerBook G3 and later.

PowerBook computers released before the 3400 do not have the hardware to support this functionality.
Published Date: Feb 18, 2012