If you've used LineIn these options should look familiar. On the Input tab select your source type (Application, Audio Device, etc.), then choose your input from the dropdown on the right. To capture an audio source go to Session -> New (⌘N) or click the + symbol on the bottom left. Not exactly convenient for long stream sessions, but perfect for short recordings. This can be reset simply by stopping the hijack and restarting it. The free version is also fully functional, with the only caveat being that it distorts audio after 10 minutes. It costs $32, but the level of control and power you have with it is unmatched.

Changing Soundflower's volume will affect them both, so it may be hard to find an acceptable balance between multiple sources. Unfortunately this method does not let you control the volume for them separately. LineIn.app/Contents/MacOS/LineIn (note the period at the start of this command, this is important.) Just change to the directory where LineIn is located and then open it through Terminal. What if you want a second one, such as a mic to go along with game audio? You can run a second instance of LineIn by using Terminal. You might notice that this method only works with one audio source.

Change back to your default output speakers and changing the volume will not affect Soundflower's volume. Because this device is not your normal speakers you will not hear the change in audio, but Soundflower is indeed being affected. To control the volume of Soundflower, hold the Option key and click the speaker icon on the menu bar, then select Soundflower. If your audio is being captured correctly, you should see the volume displayed visually in the meters. To route your audio simply select your source device from the top right dropdown menu, select Soundflower (2ch) from the menu below it, then click Play Thru.

This also lets you capture specific audio sources without capturing all desktop audio. In this manner you can have any number of audio sources routed through Soundflower and into your stream.

Soundflower is the chosen audio device in your stream software.

Game/mic audio are captured by Audio Hijack Pro or LineIn.

For a free option there's LineIn (with limitations), and for $32 there's Audio Hijack Pro which is the easiest and most robust option. Once Soundflower is installed you need to decide which software you want to combine it with. The basic idea is to take audio from one source and send it somewhere else. If you want to stream audio, the first order of business is to download Soundflower, which is an audio routing utility. Firstly, if you only want to record audio then you can do so with just Audio Hijack Pro, WavTap (supposedly conflicts with other audio software/devices), or your capture device's software.

Audio hijack mac