Roon ARC 32-bit Floating Point WAV Playback / Dithering

When I play WAV files in Roon ARC that have a 32-bit floating point bit depth, Roon ARC dithers and converts down to 16-bit. Can they be played somehow at their native bit depth or can they be converted to 24-bit in the signal path without dithering?

I have confirmed that the DAC I am using supports the 32-bit float PCM format. These files can be played losslessly through the DAC via Roon itself (not Roon ARC) on a non-mobile OS. I do have “Automatically pick best quality” turned off in Roon ARC and both WiFi and Cellular are set to “Original Format” but conversion to 16-bit/dithering still occurs.

What platform you on iOS or Android?

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Can you show the signal path from arc playing one just to see if anything stands out.

There should be no 32-to-16 bit conversion during playback. As you said, I’d expect a conversion to 24bit at most. Please share the signal path.

As a side note, while not really necessary, I believe Roon also dithers 24bit.

I’m not familiar with iOS. Does anyone know if this is an iOS output device limitation?

On the same phone does it work if you use it as an endpoint at home via Roon not arc. iOS doesn’t seem to support 32 bit wavs from what I see as the DAC in Roon isn’t actually fed back to Roon due to iOS limitations it might be related to this. Just guessing here but trying it via regular Roon to same device and DAC to see if it’s the same will rule out if it’s just ARC or a Roon iOS thing in general.

I do see a lossless signal path on iOS when I play 96Khz / 24-bit WAV files.

Can you share your playback quality settings in ARC?

It converts to 24-bit, CrystalGipsy, when used as an endpoint in Roon (not ARC). I’ll provide the signal path in just one moment.

Here are the playback settings, Marian.

Thanks. As far as I can tell, it should work the same as for non-ARC, so this seems like a bug in ARC.

You’re welcome, Marian. I appreciate your attention.

Seems like it’s not working as it should via ARC then when it should. I would move this to support the and tag@support. @moderators can you move it please?

Thank you, as well, CrystalGipsy.

It all depends on the converter in the device running Roon. Playing to iPhone internal DAC may happen differently than playing to an external Dragonfly or Schiit Modi connected via the camera connection kit. In the end, the final audio device rules.

We have validated that my external DAC can in fact play 24-bit streams from iPhone through Roon ARC without conversion.

Why then does Roon ARC convert to 16-bit instead of 24-bit when playing 32-bit streams?

All of the results above are with an external DAC bypassing the iPhones internal converter.

I would also like for the dithering aspect to not be buried here. It is my understanding that 32-bit float streams can be converted down to 24-bit (fixed) without dithering.