Audio interface not working with FP4, driver problems?

Hi everyone,

I just got my FP4. Unfortunately I got the wrong USB-C to 3.5mm dongle (the fairphone one was sold out and I didn’t realize some don’t have a DAC). But now that I’m trying it with my class-compliant (UAC2) audio interface (a Keith McMillen K-mix) with a USB OTG dongle, I’m not getting any sound to my headphones either. It recognizes it as “wired headset”, but that’s it. In audio evolution mobile it is working properly with their drivers, but not with the stock Android drivers. And I can’t use their drivers outside the app.

UAC2 isn’t a new standard at all, my particular interface was released in 2016. So I didn’t expect this to still be a problem 6 years later. I’ll get a different USB-C DAC for traveling asap anyway, but at this point it’s a bit unclear to me which ones would actually work. I understood that all class compliant DAC’s are supported, but that’s clearly not the case.

Does anyone know a workaround? Or are only UAC1 DAC’s supported?

Maybe the Infos to the working dongles of this list give a hint


Hi and welcome!

I just did a quick test with my computer’s external DAC (also UAC2 compliant, actually a digital interface – Mackie Onyx Producer 2x2) and my FP4 didn’t even connect to it.

I suspect that was at least partly because my phone is not able to provide enough power, so maybe that’s something you should check as well. Audio equipment can be quite power hungry. Also had to use a dock to convert USB-C to USB-A to USB-B, so multiple points of failure in my test.

I can confirm that UAC1 works fine (I use a FiiO BTR3K all the time), but I don’t see a reason why UAC2 shouldn’t work.


Mine does power up and with Audio evolution mobile it does work properly, so it really seems to be an android driver issue.

Thanks, that helps. I’ll have to do some digging. If I buy a dongle, I ideally want one that can drive 250 ohm headphones reasonably well. Many of them don’t seem to give clear specifications unfortunately.


Maybe this one?

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Thanks! That’s perfect for me! I went with the Sharkoon mobile DAC PD. Same DAC, but it also lets you charge your phone while using it, doesn’t have a flimsy cable and it has a mic preamp.

It works great with both my high impedance headphones and (lower impedance) IEM’s. The noise floor is just about noticeable with my IEM’s at low volumes, but waaay better than the built-in DAC in my old Nokia 8, so not a real issue. It’s a lot better than the DAC in my laptop too, so I can use it for that too when I’m not using my audio interface.


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