2ch or 6ch track sounds better through a stereo system?


I am running Volumio 1.5 on a Raspberry Pi B with a HiFiBerry DAC connected to a stereo system.

I have a concert DVD that I want to rip which contains following audio tracks:
2ch ac3 192kbps
6ch ac3 448kbps
6ch dts 1536kbps

Which one of these tracks should sound better (in theory) through my system, the 2ch track because my system is also stereo or one of the 6ch tracks since they have higher bitrates? Can someone with some experience and knowledge comment on this please?


Hello ECantona,

I would take the latter one. DTS offers from those 3 Audio tracks imho the best audioquality.
So, what you can do, is to extract the audiotrack (tsmuxer or so) and then make a recode with the program xrecode from 6ch to stereo 2 ch with 24 bit and 48 kHz samplerate in flac or wave format. Don´t resample it to 44,1 kHz, because then you will loose quality. It´s much work, especially if you want to cut it in single tracks and tag all the tracks manually. But its worth the work! I´ve done this before with the Blu-ray “25th Anniversary Rock and Roll Hall of Fame Concert” and the quality was much better as the CD´s of this concert.
Have a nice day


Hi from9to5,

Thank you very much for your reply, and a big sorry because I have just seen your post. I was thinking that I would get an email when there is a reply.

I have done some listening tests (well… as good as it gets) and checked sound volume for different frequencies using Spek. The screenshots are attached. It seems to me that 2ch version is kinda remastered. High frequencies are much stronger in 2ch version as shown in the spectrum analysis and this definitely makes it more vibrant, 6ch versions sound almost muffled compared to it.

I have not converted 6ch to 2ch for my listening tests though, I have ripped them in raw format and played directly through vlc on the same sound system (except raspberry pi part of course). I wonder if a capable converter would make a better job than vlc (or if such a thing is even possible). I also wonder how these 6ch versions would sound in an appropriate sound system. I bet they wouldn’t sound muffled, but is it normal that they sound almost muffled through a stereo system?



The way you downmix 6-to-2 may affect the quality more than listening to the original, lower bitrate 2ch.
If you can, use the 6ch without downmixing, I suppose the additional channels will be simply ignored.

And looking at the spectra doesn’t help much, we are not oscilloscopes.

Thats correct, the way you mix it down from 6 to 2 Channels will have an influence.
I´ve done it with XRecode directly to flac. My result with downmixing the DTS 48Khz 6 Channel Track was better sound than the stereo cd. The dynamic was better cause the sound was obviously limited on the stereo cd. The very low frequencies are missing on the CD, the footdrum on the downmixed flac was very clear and hard.
But I think all this depends on the overall quality of the sound, if they used a limiter during recording, if they cutted the higher and/or lower frequencies and so on. In my case, the stereo track on that special blu-ray was indeeed frequency cutted and limited, the 6Ch track wasn´t.
So, I think you have to try to use different methods of downmixing or not on Volumio. Perhaps you can switch your blu-ray player to downmix channels to stereo and plug the output signal (Chinch) to your stereo and check the quality with your headphone while hopping through the different audio tracks. That can give you an impression, which audio track sounds best for you.


I have googled how to downmix from 5.1 to 2 and found out these forum topics:

The key is to find out appropriate downmixing coefficients which define how much of each input channel will be included in each output channel. As far as I understand, there is no silver bullet here. It really depends on the source and it is quite subjective. A player usually have a set of default values for these coefficients, but they can be different for another player. They can even change from one version to another of the same player. And if player A gives (subjectively) better results than player B for DVD X, this doesn’t mean that it will also give (again, subjectively) better results for DVD Y.

Hopefully, downmixing coefficients can be included in ac3 and dts files and some DVDs come with audio tracks containing these coefficients – most probably chosen by the sound engineer or alike. I don’t know if audio tracks in my DVD in question has them. I don’t know how to check this (yet), I will look for it when I’ll have the time. Until then, since I am looking to reproduce the DVD audio as close to the source as possible, I will stick with the 2ch track which is (in theory) downmixed/mastered by the sound engineer. Of course, there is the sad fact that 2ch track has lower bitrate than 6ch tracks (if they are comparable at all), but I still think, at least for now, that it is better than subjectively mixing 6ch down to 2ch.