B81 ARC conversion to 48kHz with USB DAC (Chord Mojo) [solved by removing and reinstalling ARC]

(Android 11; Fairphone 4)

I fail to pass native formats to Chord Mojo over USB.
With same connection and phone settings USB Audio Pro recognises the Mojo (by name) and happily passes on native formats from Qobuz and switches between sample rates. Arc converts all rates to 48kHz.

(@Suedkiez - I understand you also have Fairphone 4 at your disposal. Any more succes with native USB playback, or suggestions on something I could try?)

Example with 96/24 source from Qobuz

Arc/Roon (note that Arc sees output as AAudio, so perhaps not surprising that everything gets resampled?)

Mojo confirms the resampling to 48kHz with an amber light .

USB audio player pro (with same phone / usb configuration)

Recognises the Mojo

And passes on native format

Mojo confirms 96kHz with green light.

I tried both ‘Roon ARC’ and ‘MTP Host’ from the ‘Choose an app for the USB device’ popup menu when connecting the Mojo. Result is same.

Yes I have an FP4 but no USB DAC, sorry

Ah, but maybe you need and want one? :wink:
Thanks for response.

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In th fresh light of morning, I reinstalled ARC, re-enabled its USB driver … And problem solved - native passthrough works fine now :+1:.

(There was btw a short crackle over phone speaker on starting play)

Hi Ozzie I was having similar problems to you, but my audio for the FIIO KA2 is all working through USB as per your post, but Roon is downsampling to 16 bit for everything.
Can you check your signal path and check that Roon is not downsampling the audio before it sends it to the DAC which is what mine does.

Like this?

Sample rate definitely as expected and hoped - see below. The Mojo won’t tell me the bit depth, but no indication of any change in signal path.


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And checked with an existing short playlist used for previous testing of sample and bit rates with different DACs. The path in Arc and the light on the Mojo suggest all is well with a range of 24bit tracks from Qobuz (But as mentioned before, there is a pretty horrible pop over the phone speakers on almost every transition)


Yes thanks yours is doing exactly what I expect it to do.
Though Mine is sounding good so I have no complaints about that.
I am guessing my KA2 is not fully supported for 24/96 on Roon USB driver, I did ask the team what DACS are supported to what level.

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I’m using bit perfect USB output via Arc successfully on my old LG6 using Android 9 with an Audioquest Dragonfly Cobalt. Initially, the volume is briefly maximum, but I think that’s a Dragonfly problem.

It sounds great. Thank you very much for implementing this. It makes me much more likely to use Arc while I’m away from home.