5.1 to 7.1 not supported for FLAC/WAV?

Hello All,

I am relatively new to ROON, a few months now. I have a couple of AV systems, a 2 channel with a SMSL DA200 and Cambridge Audio CXN (V2) to leverage MQA from Tidal. However I found Tidal lacking in some older content I liked and the CA Streamagic software was horrific for using local NAS based content. So ROON was the answer for me. For the 2 Channel system there are no complaints. I also have a 13 Channel system using an Anthem AVM. I was hoping to leverage this for 5.1/7.1 with the Cambridge Audio as I no longer needed it for the 2 Channel because the ROON server is directly attached to the SMSL. I was disappointed at the relatively poor capabilities of the “ROON Ready” device to say the least. So cutting to the chase, I went with a ROON Bridge and got an Okto DAC8 to do native 7.1.
This where my question arises from, what I am seeing is that DSD/DSF 5.1 content is being properly sent as 7.1 and all of the channel inputs are lit up on the DAC(It shows what input channels are active on the front display). However when I have 5.1 content in FLAC or WAV format the two back channels are not getting input. I have run a test with PF WYWH which I have in DSD format, a downloaded “lossless FLAC” and a conversion of the DSD files to FLAC as well. Has anyone else noticed this behavior? The Multichannel page that I have reviewed seems to indicate that this is not the expected behavior, any thoughts would be appreciated.

Thank You,


In the Settings Audio for the zone your using, device setup, show advanced, with the channels set to 7.1 Roon adds a switch to swap the sides and rears.

Some devices use the sides in MC and some use the Rears. No idea why some are different. I use this switch when I want to change from rear to sides or sides to rears.

You might give that a try.

Thanks Mike, between DSD and FLAC playback, nothing changes for device setup, just DSD uses 8 channels and FLAC uses 6.

Michael, I concur with Mike’s advice. I too have an Okto dac8pro, with Roon set to 7.1. With 5.1 content, doing the rear swap works for me. However, when I listen to 5.1.2 Atmos content, I need to turn the swap off. JCR

excuse my question but how do you listen to atmos content through Roon?
once you convert a ripped bluray to Flac you remove the atmos meta data. sure you can use software to combine channels or use MMH to convert the files into Flac with all the channels, but its not really atmos anymore.

Agreed, simply ripping WAV or FLAC files off the Blu-ray won’t preserve the spacial cues. However, the spacial cues are saved by using the Dolby Reference Player and the decoding Atmos dialog of MMH. See this article:

I listen to Atmos in 5.1.2, which MMH now supports. Because that is 8 channels, an Atmos recording decoded thusly (and saved as WAV files or only then converted to FLAC) can be directly played back in Roon. It works very well. JCR

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Thanks for sharing that link, I just read and very good.
Does Roon support decoding of these files or do you have to use the Dolby player for this purpose? I didn’t think Roon supported these files.

Currently I use Blue-Ray Audio extractor for Room and Makemkv for Plex server. Understanding that I am not getting ATMOS from Roon.

“The Dolby Reference Player is still reqquired, but is only used by MMH.”

a one year license for that dolby RP seems to cost 400 USD per year.
and from what I understand it will just convert the spacial cues into the Flac stream.
but not as meta data that can be altered through a dolby atmos receiver … once its in the Flac stream its kinda baked in right?

its like stripping dolby vision of a bluray movie and trying to get kinda close enough with HDR10.

Hi All, not sure how this became an Atmos ripping conversation, there should be no metadata maintenance requirement, it is simply a 5.1 > 7.1 surround channel split question, why does it work for DSD source and not FLAC/WAV from the same recording, they both use SR/SL but with the DSD it uses RR/LR as well.
I did some testing based on Mike and Jeffrey’s advice. While the swapping did enable the rear channels it just swapped those for the surround channels and for DSD it was 7.1 channel and for FLAC it was 5.1 channels, so no difference.

I think it’s time for a support ticket as this seems to be some kind of bug. @Jeffrey_Robbins I am curious if you have different results. The source is Pink Floyd Dark Side of the Moon DSD/DSF 5.1 channel download and then converting it to FLAC from those files. But do you see all 7 channels being used for FLAC based 5.1 source?

Thanks to all for the responses.

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If fixing that takes as long as waiting for quad channel audio to work we might be waiting for a while :slight_smile:

What are you trying to accomplish here? To be clear, Roon does not have any built in surround upmixing routines. Roon is different from an AVR and will not expand 5.1 multichannel to 7.1 multichannel. If sending 2.0 stereo or 5.1 multichannel as 7.1 multichannel, Roon simply is adding silent channels to the mix.


I think that is correct. I’ve attracted a spectrogram of Money from Pink Floyd in three formats: DSD5.1 with the swap in place; DSD5.1 without the swap in place and FLAC Dolby Atmos 5.1.2 without the swap in place. The full 7.1 channels play out only for the Dolby Atmos mix.

So if you are trying to get the 5.1 material to spread out over 7.1 channels, I think it’s a feature request and not a bug. JCR

Four and a half years and counting… :+1:

It is a limitation of Roon. How they manage this I don’t know. It seems as if the 7.1 Channel lay-out setting in Roon blocks the Surround Amps to upmix 5.1 to 7.1 or more. I have the same problem with my Denon AVC-A110 and previous versions. Switching to 5.1 does not help either. Swapping the Surround channels in Roon is useless too as it just does that and - as you already noticed - you would need to go to Settings again for playing other Surround content. As a matter of fact the channel Swapping was intended for Quad files but this does not work correct either, but that is another story. What I do know is that if you play the same 5.1 flac file through - for instance JRiver or Foobar - you get back the ability for the Surround Amplifier to upmix it to 7.1 and more.

Thanks to all who responded, it’s interesting, when you check the signal path 5.1 > 7.1 shows as one of the steps, and on the DAC8 all 8 channels show input with the DSD5.1, but as mentioned by Andrew, it seems these channels are silent, however with the FLAC version only 6 of the channels show input, and not surpisingly, it’s the two silent channels from the DSD5.1, As you can see from the photos attached.

DSD does not have a digital zero, per se, because 101010…, 110011…, 111000…, etc., all reproduce at the digital noise floor in the passband. PCM, on the other hand, has a defined digital zero that can be recognized as such.


The side/rear switch works well for my situation. In my roughly 24 by 17 living room the main seating position, recliners, are in the middle of the room. If I’m up and moving around or using other seating, which is most of the time, I want the rear speakers in use for multi-channel music. If I’m sitting in the recliners I want the side speakers in use as the rear speakers, 10’ behind the recliners, are blocked by the headrest . It is convenient to have a choice. I don’t know what the original intent was or how anyone else uses it.

$400 one time license for the DRP. The decoding function continues to work fine after the one year expiration.

Yes, the Atmos array selected is baked in. For me, it’s 5.1.2 so I can use Roon. But you can do 7.1.4, for example — in which case, JRiver would be a good playback software choice.

I saw a reference as well to the 4.0 / quad debacle. My answer is to use MMH to add a blank center channel, bringing the channel count to five, which Roon reliably recognizes. JCR

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Thanks Andrew, I guess that explains it.