Last year in LG's V20, it introduced the 32-bit Hi-Fi Quad DAC, allowing for better audio quality, even when using ordinary headphones. That's been improved in the V30, with something that LG is calling the 32-bit Advanced Hi-Fi Quad DAC.
When I reviewed the V20, I remarked, "now I kind of want to listen to all of my music on the V20", and I feel the same way about the V30. It sounds fantastic, and testing this device is ruining my ears for other phones. At the briefing that I had with LG, I got to try out the V30 next to an iPhone 7 Plus and a Samsung Galaxy S8, and the difference was clear as day.
Just like in last year's model, the feature is turned off by default, for some reason. When you plug in a pair of headphones, you'll be prompted to turn it on if you wish to do so, and you should.
The big difference in this year's model is that you get more configuration options. With the V20, you could really only configure the balance in the left and right speakers.
As you can see, there are a lot more options in the V30. I am by no means an audiophile, so I'm not the best person to go into detail about all of these. I can say that I've tried out all of these settings with different types of music, and some are better than others depending on what you're listening to.
If you have something of an eclectic taste in music, you'll probably find yourself changing these around from time to time, which is pretty simple, as it can be done by going into the Quick Settings and holding the icon for the Hi-Fi Quad DAC.
All I can really say is that it's awesome, and I don't even use expensive headphones. I typically just use earbuds that come with whatever phone I'm using, and even with these, the difference is wonderful.