Oh no, you're referring to the "USB DAC" setting in Settings->Audio. What I'm talking about is the "USB output mode" in the settings sidebar of of the Music App (not device settings). Only when I set this to "OFF" could I get the G3 to work with the M6.

I've tried the G3 with the Dunu DK-3001 Pro, and when using the -30dB volume setting I get a very usable volume range and only very slight hissing. The hiss is only noticeable when no music is playing and I initially plug the headphones in (effectively going from dead silent, and then hearing...

Anyone managed to successfully get the G3 to work with the Fiio M6? It seems like when I first plug it in the light comes on, but after that there's nothing.. No light, and no sound when I start playing music. In fact, the Fiio gives no confirmation of an external device having been connected...

Nah, not sure on the manufacturing date. The best info I have is that it's from the batch that was sent to Samma3a in May

Interesting.......I checked again, mine definitely does NOT have any markings.

Woops, deleting this reply as I forgot I had already made a recommendation in this thread