SoundSource

SounceSource lets you adjust your input, output, and sound-effects devices and volume settings in mere moments, right from the menu bar. Enable soft play-thru of input devices to your desired output, so you can hear sound coming in through any microphone or other source. With SoundSource, you get fast access to your Mac's most important audio settings.

• Instant Audio-Device Switching - With just two clicks, you can switch the audio devices your Mac is using for input, output, and even sound effects.
• Fast Volume Control - SoundSource provides easy access to the volume controls for your audio devices as well.
• Audio Play-Thru, Too - SoundSource's Play-Thru window makes it easy to monitor the audio coming from any input device.
• Comprehensive - SoundSource gives you one place to go for all Mac's most important audio controls.
• At Your Fingertips - With SoundSource running in your menu bar, your audio controls are always available.
• Lightweight - When you don't need SoundSource, it stays out of your way.

• Control Audio on a Per-Application Basis
• Sweeten Any Sound With Audio Effects
• Get Fast Access to System Audio Devices
• Complete list of changes can be found here