I know it's from a very old post but did you ever get the 4x dac to work outside or happens in you're rooted lg v30?
To Root or not to Root is my question?
https://www.head-fi.org/threads/lg-v30.858933/page-261#post-14466905
The DAC is always active when you enable it. No need to worry about whether all four DAC modules are being used, as it doesn't affect sound quality.
If you want to root, do so before Android Pie arrives in the next few weeks. Once updated, you probably won't be able to root anymore.
Root can make it easier to force HIM, say for planar magnetics. Also allows you to keep updating with custom ROMs after LG stops updating. But of course there are risks, and it requires some skill, study and upkeep.