Route USB mic input to System Audio output for Camtasia 2? I'm using Camtasia 2 for the Mac on El Capitan (10.11.3). I need to use two microphones so the audio will record to separate audio tracks. Camtasia 2 has one input audio source that does recognize the digital audio interface, a MOTU 828 MK3.(Only for one channel, but that's OK). This is normally used to record from a USB microphone.

The other audio source you can record from into Camtasia 2 is the System Audio. The System Audio is what plays the computer's alert sounds. I'd like to use the System Audio as a second audio input source from a plug-in USB microphone. It would be the only USB mic used in this configuration.

So it appears what I need to be able to do, is route the USB mic's output to be part be added or replacing the System Audio. This way, the USB mic can be recorded to the System Audio track, thus giving me a second microphone to be used.

How can this be accomplished? Is there some set-up using Audio Midi and Soundflower that can do this? Or is there some other sound utility which can do this?

It looks like I need something which will route the USB mic audio to be played out the System Audio so that Camtasia 2 will record it.

The goal is, so the net result is that MOTU 828 MK3's output gets recorded to the USB Mic audio, and the USB mic actually plugged into the USB on the Mac will be recorded into the System Audio.
Rogue Amoeba's Loopback will allow you to route virtually any input/output to/from any Mac application. It is easier to use than Soundflower, and you can create multiple routings (which Soundflower does not) -- but it is a paid (and supported) app (unlike Soundflower).