Your Mac's Sound Preference Pane is the go-to place for choosing audio inputs and outputs, but it isn't the only place you can go in OS X to manage your Mac's sounds. Even though Audio MIDI Setup may sound intimidating, it's loaded with controls that go far beyond what its name implies and can help you fine tune the audio quality your Mac pumps out.
You can find the Audio MIDI Setup app tucked away in Applications > Utilities. Once launched, you can choose any audio input or output available and make adjustments that go beyond the basic features in the Sound Preference Pane.
My MacBook Pro, for example, has the usual built-in speakers for output, but I also have Audioengine's D3 DAC connected to a USB port. It's a 24-bit digital-to-analog converter that gives me much better audio than my Mac's built-in audio chip can manage. I can set my audio sample rate to 44.1 kHz, 48 kHz, 88.2 kHz, or 96 kHz -- but only from Audio MIDI Setup.
Audio MIDI Setup lets you control sample rates for your speakers and mics
You can set the sample rate for audio output devices by first selecting the device from the left-side column, and then clicking the Output tab. Now use the Format pop-up menu to choose the sample rate you want. Higher is generally better, but don't bother to choose a setting that's beyond quality you can hear; if it doesn't sound better to you, don't bump the sample rate up, and there's no point in wasting processor time on something that isn't giving you audio quality beyond what you can hear.
Some audio outputs support multichannel. You can set that by clicking Configure Speakers, and then choosing Stereo or Multichannel. Use Stereo for 2-speaker setups, and Multichannel for surround sound setups.
You can set panning for multi-channel speaker setups
Every speaker connected to that output will appear, and you can assign specific channels to exactly the speaker you want. From here, you can also drag the blue dot to set panning.
I set my D3 to 88.2 kHz because that sounds great with my Audioengine A5+ speakers. Yep, I'm a little spoiled with my Mac's audio setup.
You can set the sample rate for input devices, such as microphones, from Audio MIDI Setup, too. My Rode Podcaster mic is set to 44.1 kHz because I use it to record my speaking voice. No surprise there considering I spend so much time recording podcasts.
There are a couple buttons tucked away at the bottom of the device list. The plus button lets you create Multi-Output Devices -- or groups of outputs that act as a set of speakers. I set up one that includes my D3 and AirPlay so I can play the same audio at my desk and through my home entertainment center. Think of it as a poor man's Sonos in that you can play the same music through speakers in different parts of your home or office simultaneously.
You can group outputs together to play audio simultaneously through multiple speaker sets
Aggregate Devices, also available from the plus button, let you group together audio outputs to create your own multi-channel system from speakers you already own. Multi-Output and Aggregate devices show up in the Sound Preference Pane's Output tab just like the rest of your speakers.
The gear button hides a pop-up menu where you can set default input and output devices, and even set specific outputs for general audio and system sounds. Translation: You can use one set of speakers just for your Mac's alert sounds. You can do this, too, from the Sound Effects tab in the Sound Preference Pane.
All audio sources, including multi-output groups show up in the Sound Preference Pane
Once your speakers and mics are set up just the way you want, it's OK to select them from the Sound Preference Pane if you don't feel like launching Audio MIDI Setup just to switch speakers. Think of Audio MIDI Setup as your super charged Sound Preference Pane.
With great power comes great responsibility, so use your new-found skills for good. Don't play crappy music. Life is too short for that.