OS X is capable of outputting 5.1 sound to your home theatre system. Depending on which model Mac you have, you may not need any outboard hardware except for a special cable. You will need a 5.1 capable system. Here’s what you need to do to get the surround sound in OS X working.
How 5.1 Surround Sound works:
Without getting too detailed, basically 5.1 Surround Sound is a six speaker system. The speaker positions are: left channel, right channel, center channel, left rear, right rear and sub bass / low frequency. In order for your home theatre system to know which channels go where and to reproduce the surround effect, the sound is encoded in Dolby Digital, DTS or Sony Dynamic Digital Sound format. So, to get true 5.1 Surround Sound, you will need speakers and an amplifier that understands either the Dolby Digital, DTS or SDDS information.
Using a Dolby Digital / DTS 5.1 Home Theatre System:
Most of the Home Theatre receivers / amplifiers will say which method of 5.1 Surround Sound they can handle. Dolby Digital / DTS is pretty common. Most commercial DVDs have this encoding on them. We’ll assume you are using a DVD as the source and have the appropriate receiver.
On the newer MacBooks, MacBook Pros and iMacs, Apple has included a dual 3.5″ audio output. It will output either analog stereo or digital optical signals depending on which cable is plugged in. To take advantage of this output you will need a special Optical Toslink to 3.5″ Mini Toslink cable for your receiver.
Once the cables are hooked up appropriately, we’ll need to check OS X’s audio preferences to make sure it’s sending the digital signals.
– Go into System Preferences and choose Sound.
– Click the Output tab at the top.
– Choose the Digital Output if it’s not already.
– Close System Preferences and Put a DVD into your Mac.
– Be sure the Audio Configuration for the DVD is set to 5.1 Surround Sound.
Note: This is set from the DVD’s menu, usually under “Setup”, “Options”, or “Audio”.
– Check your receiver, you will hear sound and it should indicate DTS, SDDS or Dolby Digital.
Using 5.1 Capable Computer Speakers:
Another way of using 5.1 Surround Sound with OS X is to use 5.1 Surround computer speakers such as the Logitech Z-5500 digital speaker system. This type of setup does not incorporate a receiver like in a Home Theatre system but will gladly accept digital audio from the optical input on your Mac, Playstation, XBox, DVD player and CD Player. When used with OS X, you’ll need the 3.5″ mini Toslink to standard Toslink cable to attach to your Mac. The setup is exactly as with the Home Theatre receiver. The difference, other than price, between these and Home Theatre systems is audio quality, power and the ability to choose your own speakers.
Other Setups / Older Hardware:
With older hardware, the built-in digital optical output isn’t present. In this case, you will need an external sound card that can output the appropriate signal. A recommended external USB audio interface that will pass 5.1 Surround Sound information is the M-Audio Transit. You’ll need a standard Toslink optical cable for connecting to either your Home Theatre system or 5.1 capable computer speakers.
Going further than DVD Player:
Using 5.1 sound that’s encoded on DVDs is nice and OS X’s DVD player will send the appropriate audio, known as AC3 / DTS, to your system. However sometimes the signal is 5.1 but enclosed in an AAC format instead of AC3. In this case, Graham Booker has a great tutorial on enabling AC3 pass-through in Quicktime. If this doesn’t work, here’s another method.