This update got rid of the extra Built-in Line Output which was good.
There's still an issue with the last Built-in Line Output which is for the far left and far right speakers (see screenshot) - if I make it default it will play audio just from the far left and far right speakers just fine, but when adding it to the Aggregate Device it still doesn't play audio from those two speakers.
The bass, center, front left and front right still work fine with the Aggregate Device though.
External Microphone still isn't showing up on Input devices in Sound Preferences as well.
Audio devices show now but the External Microphone Input doesn't show and I need that too.
However, Aggregate Device works for the two front speakers, middle speakers and bass. It doesn't work for the far left and far right speakers yet - but we're close now.
Vox detects only two of the Built-In Output's. Built-In Output and Build-in Line Output to be specific, it's missing one Build-in Line Output. On the left side of the screenshot, the first Build-in Line output under Built-in Output doesn't play any sound at all. The last Built-in Line Output plays the sound for the far left and far right speaker.
Btw, had the default audio outputs changed while I was testing each 2ch speaker output.