About the audio ports on Mac
Your Mac includes one or more audio ports. You can use these ports to connect to headphones, speakers, or an audio system.
Other ports can transfer audio data as well. Some speakers and professional audio interfaces connect to your computer’s USB port or FireWire port . And some video ports transfer both audio and video data.
Headphone: You can use this port as a combination headphone and line-out port. Connect headphones or speakers using a standard audio cable with a 3.5 mm metal plug.
Headphone out/optical audio out: You can also use this port for both optical digital audio output and analog audio output. Connect external speakers, headphones, or optical digital audio equipment. For analog headphone/line output, use a standard audio cable with a 3.5 mm metal plug. For optical digital audio, use a Toslink cable with a Toslink miniplug adapter or a fiber-optic cable with a 3.5 mm plastic or nylon optical plug.
Analog audio in: You can use this port to connect stereo equipment to your Mac with a stereo miniplug-to-RCA cable adapter.
Audio in/optical audio in: You can also use this port for both digital optical and analog audio input. For analog audio input, use a 3.5 mm mini phone jack or a stereo miniplug-to-RCA cable adapter to connect stereo equipment. For digital optical audio input, use a standard Toslink cable with a Toslink miniplug adapter. Digital optical audio input uses the S/PDIF protocol.
Analog audio out: You can use this port to connect self-powered speakers, MP3 and CD devices, and other audio equipment to your Mac.
Optical digital audio in and out: You can use these ports to transfer stereo or encoded 5.1 audio using the S/PDIF protocol over Toslink cables and connect to decks, receivers, digital instruments, and 5.1 surround-sound speaker systems. Use standard Toslink cables, or fiber-optic cables with a 3.5 mm plastic or nylon optical plug.