Roon ARC and DSD

Roon Core Machine

iPhone 13 Pro Max, 512gb, iOS 16.0

Networking Gear & Setup Details

connected to Mac Studio running Roon Core over WiFi/LAN for purposes of this post

Connected Audio Devices

iPhone to Chord Hugo 2 via USB

Number of Tracks in Library

small music library

Description of Issue

I am attempting to use “DSD Playback Strategy” = “DSD over PCM v1.0 (DoP)” to play my DSD files.

Oddly, I have only been able to play some DSD files and not others with no apparent differences between the files (same sample rate, etc). Following advice in this section I seem to have worked around this somehow by turning off “Automatically pick best quality” and “Volume leveling”. This seems to be a bug. Is it going to be fixed in an upcoming maintenance release ?

Also, the app crashes constantly. Is this going to be fixed in an upcoming maintenance release ?

My primary reason for posting is, after initiating the work arounds mentioned, and getting DSDs to at least play, I’m not clear how to interpret the resulting signal path displayed. I’m getting this:

and something similar with DSD128 files. Can I assume this means the output to my DAC is bit perfect DSD64 and DSD128 respectively ?

Also, it appears Roon ARC is resampling any DSD with higher resolution than DSD128 to PCM even though my network, phone and DAC are all capable of handling up to DSD512. Is this a bug or a limitation ? Either way, is it going to be fixed in an upcoming maintenance release ?

You should know all Chord DACs convert DSD to PCM internally.

However, in saying that, the “Lossless” and purple stars do verify that the original source rate is being sent to the DAC. I assume this is happening over DoP. DoP reduces the overall bandwidth available to the USB audio interface (it has to pack PCM data on top of the DSD). I don’t know if that is the reason. Do you have a signal path of a DSD > 128 we can look at?

And, as you found, yes you must override the “best quality” and lock “original” as your option. Turn off all processing including volume leveling. That’s the only way ARC will pass the original file format, untouched, to the DAC. This is no different than the requirement to turn off all DSP in the Remote. That’h not a bug.

I cannot comment on app crashes but you’re taxing the USB interface with these high bitrate files. How good is your cable? How old is your phone? Have you cleaned the lightning port recently?

Just read a review that says DoP mode on this DAC is limited to DSD256 while another review says its limited to DSD128 in DoP. I hope someone can verify but right now that seems to be the limitation you’re running into.

Thanks for the response ipeverywhere.

The signal path of DSD128 looks exactly the same except the “Source > DSF DSD64 …” is replaced with “… DSD128”. For one at a higher rate, here’s a DSD512 file:

This one’s also confusing in that it states, “DSD to PCM conversion” but lists, “DSD512 to DSD64”. Then under “Sample rate conversion” it shows, “DSD64 to 705.6 kHz”. Also, the Hugo 2 still shows it’s seeing DSD from this (but isn’t capable of displaying the specific DSD rate).

I’ve tried several cables that I would have said are good quality and they all behave the same. It’s a good thought though, I’ll look again to see if I can find a better one. Also, I’ll try cleaning the port though the phone is kept in two protective cases and is less than a year old.

I do think the crashes occur more frequently with DSD files so you might be right about that. The app does crash a lot in general though. Also, so far I have had very poor luck connecting remotely even with a four bar 5G cell signal. These tests have all been via nearby WiFi/LAN.

Thanks again for the response !

Certainly DSD512 you’re limited by DoP. Roon will need to comment on if the expected behavior is to reduce the DSD rate or convert to PCM when the DSD won’t “fit” in the DoP.

I believe the only way to use native DSD on that DAC is with Windows but I’m no Chord expert.

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Hi, I am having the same issue with my iphone 13 pro max plus ifi go bar gold. The ifi supports DSD256 but when I play a DSD256 it gets converted to PCM. DSD64 files play natively/ lossless.

Yeah, frustrating. I can’t help noticing Roon hasn’t offered a thing about this …

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Any chance that this is an apple issue with ios16. I just tried the onkyo hf player and had the same result

I just tried DSD256 with my Chord Mojo and it showed as lossless plus the correct led on the mojo, interesting.

Yeah, it’s weird. My Hugo2 shows the DSD light too though it can’t indicate which resolution it’s seeing.

I know the DSD256 files are only a tiny portion of the collection, but if your whole setup is in theory supporting native playback you want it to work, right? Any other ideas / views?