Routing audio around on a Mac, between software applications, or from multiple sources including hardware instruments, microphones, and the like, can be challenging when your needs go beyond simple playback. So if you’re making podcasts, working in audio production, or just have a need to get audio from one place to another on your Mac, read on…
One helpful tool built into macOS is a pair of Audio Units (AU’s), Apple’s AUNetSend and AUNetReceive. As the pair of names implies, the pair is comprised of an Audio Sender, and an Audio Receiver.
Both the Sender and the Receiver require an Audio Unit Host. An excellent free option is Hosting AU.
You can run as many pairs of AUNetSend and AUNetReceive as your host can accommodate, and have excellent options for the Data Format of the Audio you wish to send:
You can also select a custom port for the Send/Receive pair to work on, and set a password for the pairing if securing the audio stream is an importance, in a live or public venue, by example.
Much of my audio routing is done to optimize the amount of processing power I can use. So the lossless audio transmission AUNetSend & AUNetReceive afford, allow me to transmit audio to multiple plugin hosts for distributed processing.
Similarly, AUNetSend & AUNetReceive are effective to set up separate audio monitoring chains. I like to have an instance of AUNetSend on a return track, this allows me to quickly send audio from different tracks out from that return track for monitoring, cueing, or processing.
You can send as many audio sources through the Sender as you like, or you can set up separate instances if you wish to send mono channels, which is also nice as you can send each mono channel to a receiver that can be located anywhere in the audio chain, allowing a great deal of audio channel flexibility for mixing and the like.
Another way to utilize AUNetSend & AUNetReceive is to use them on multiple tracks within your DAW or plugin host. You can use them as a second audio source or receiver on a track, and you’ll probably think of other ways to fit your needs.
Below I have Ableton Live 10 with 2 Instances of AUNetSend, on Track 2, and on A Return Channel. Both are sending Audio to Hosting AU, where as you see I have an additional 3 slots below each instance of AUNetReceive, to process my audio through different AU & VST Effects, before the Audio is ultimately played out through the Presonus Quantum audio interface.
I could just as easily here, set up pairs of AUNetSend in Hosting Au, and route the processed audio back to Ableton Live with receiving pairs of AUNetReceive, or forward the audio on to another plugin host for recording, like Audio Hijack (which hosts AU plugins).
Audio Hijack from Rogue Amoeba is another excellent audio router for the Mac, allowing you to record and route audio from and to any sources. Here’s an example of AUNetSend & AUNetReceive in Audio Hijack:
I’ve noticed AUNetSend & AUNetReceive are often overlooked as excellent free solutions to overcome a good many situations in which audio routing with and through multiple inputs and outputs is needed. With the free AU plugin host, Hosting AU, the Mac gains some robust, low-latency audio routing with its built-in plugins.