Decent, but only when it actually worked.
My unit came defective, as it worked about half the time, and I had to fiddle with the cable a crazy amount (even used other cables to see if it was the cables that came in the box, but it was the unit). I would plug it in, and the power light wouldn't turn on. I would switch to my computer, and it wouldn't work either. I would then either have to wait approximately 10 minutes and come back to see if it did work. After installing the drivers, my computer also had lots of trouble detecting the device. The blue light would be on, and there would be no "Zorloo ZuperDAC-S" device. I would have to unplug and plug it back in multiple times and wait a fair amount of time, and many times after plugging it back in the blue light did not turn on again. When it did work and it was plugged into my PC, there would also be an occasional hissing noise when the DAC was at full volume or a few steps below. But, when there was no hissing and it worked, it did do its job. On higher power headphones, bass was a bit punchier and overall sound was fuller (semi-noticeable). I could barely hear a difference on my 1More Quad Drivers when plugged into my Galaxy S9, though. Side by side there is a slight difference when using .flac files, but without .flac and just casually listening, there was almost no difference.
TLDR: For the casual listener, only get it if there are serious problems with your onboard sound and you catch this drop again for $40 bucks, which is how much I got it for. Beware of build quality though, many users (including me) report bad devices. Because my device only works half the time, I will be refunding my unit.
Would not recommend to a friend.