Well, first of all: I was using the G5 on macOS, with a Antlion ModMic v5 and open-back headphones. I have no complaints about about the sound quality on the Mic or headphones.
Though, I should mention, while the Mic worked fine on Skype,
it refused to deliver acceptable sound quality in Discord. With my old interface the sound of the mic was fine, I don't know where the problem came from. Of course it might be the program, but I doubt it.
So then, let's begin the story of me trying to use the G5:
• At first, the G5 worked flawlessly. no sound quality complaints or similar.
• Then, when I turned on my computer the red LED at the top was flashing, no sound. It was a quick fix by unplugging the USB cable and plugging in back in.
• A little later, even that didn't work, so I had to restart the computer, which fixed the problem that time.
• After then, restarting the computer and unplugging didn't have any effect. Eventually, this time I got it to work by plugging it into my USB hub (which is specifically not recommended in the manual).
• Months pass, the device works (minus the mic problems in Discord described above), until one day, no input sound is present whatsoever. The line-in seems to have stopped working completely. I could find no solution up to now, am sending it in for warranty.
Looking around online, I have found a couple others reporting similar problems. I might just be one of the unlucky few, I guess I'll see when it comes back from warranty.