Steps to reproduce:
1. Open a QA-supplied project ("AudioCrashRepro.zip")
2. Open Edit - > Project Settings -> Audio
3. Set Default Speaker Mode to Quad (I've managed to replicate it with other options as well, but most often the crash happened with this one)

Reproduced in: 2018.3.12f1, 2019.1.0b10, 2019.2.0a10
Not reproduced in: 2017.4.25f1*

Note:
*No feature to create AudioManager Presets

As the user stated, this issue is not deterministic, but I've managed to successfully replicate it every single time within 3 minutes of testing.

The crash is happening more often right after saving an Audio Preset and changing the values on the Audio Manager

Sending over more videos than usual to prove that this repros

If the crash does not occur at first, try steps options:
- Leave both the Project Settings panel and the Inspector visible at the same time.
- Duplicate the presets many times.
- Modify the presets' values randomly.
- Multi-select the presets.
- Try having multiple Inspector tabs.
- Apply the modified presets to the AudioManager.