USB + PCM -> DSD conversion

[SwissBear]

When I was in tough discussions with Devialet Support about working with AIR, they kept encouraging me to come back to USB, which was not an option for me as I was trying to have AIR work. But as the young lady insisted that USB would allow me to use DSD files as well, I kept this in my mind.

Having sorted out other room correction issues I had, getting rid of an excess of sub-bass energy reflection in my room via the high-pass filter of the Devialet, I could remove my signal processing equipment from the chain and contemplate the possibility to try PCM -> DSD conversion.

I did that last night and was quite impressed with the result.

Settings are quite easy in JRiver :

[img][/img]

Has someone else tried that ? What are your thoughts ?

[Confused]

I have to say that I am a bit of a purist, so to me the thought of upsampling to DSD, to send to a Devialet which by necessity converts DSD back to PCM is simply wrong and cannot be good for sound quality. Then I had a demo of the dCS Vivaldi upsampler and clock. The demonstration was performed mainly with good old 16/44.1 material. The dCS rig was upsampling to DSD, this was then being sent to the Devialet via AES/EBU. It sounded superb. However, to me this was wrong. As the ADH core architecture is PCM, this means that you are taking a PCM file, converting it in the dCS to DSD, sending DSD to a Devialet that then converts the DSD back to PCM such that it can be utilised in the ADH core. As a purist, I thought this was just plain wrong. Anyway, at my request, the dCS rig was then was then set up to feed the Devialet PCM. We listened to the same tracks, and quite simply, it did not sound as good. All this stuff does baffle me a bit, but I know what I heard and if implemented well, it appears to work.

I have seen a couple of other posts suggesting using DSD DACs, feeding the Devialet an analogue signal. I am not sure if anyone has tried this though!

My thoughts are that this is definitely worthy of investigation. Via a very (very!) expensive dCS rig, I have experienced DSD upsampling producing stunning results into a Devialet. Can similar, or at least good, results be achieved using upsampling software, using I guess a very powerful computer, or maybe by converting files to DSD, and then playing as pre-converted DSD files? I have no idea. All I can say is that this is an interesting topic and something I plan to investigate and maybe experiment with, when I get some decent free time.

[Antoine]

I agree with Confused. It's a lossy process so you may actually like the character of the added distortion or the different filters used. I also think that the real advantages of DSD upsampling won't really show up unless using much higher DSD bit rates, higher than DSD64 and excellent upsampling algorithms. I'm no fan of JRiver BTW but would trust HQPlayer based on other users' experiences. Best would probably be a DAC that supports native DSD input, like the T+A DAC 8 (up to DSD512)

http://www.thewelltemperedcomputer.com/KB/DSD.htm

176/24 PCM and DSD64 are about the same resolution, they just have different distortions. Thus it seems a matter of preference which one is "better". However, converting between them is not such a great idea as the mismatch retains the worst aspects of PCM (smeared transients from the filters) and DSD64 (high frequency noise that starts at 25 kHz). DSD128 does not seem to have the problem with high frequency noise that DSD64 has, so this tradeoff seems moot, at least on my system.

Tony Lauck

[SwissBear]

Hi Confused and Antoine,

Thanks for your thoughts.

Interesting to read that dCS produced a stunning experience to your ears Confused. Might also be that the DAC of the D900 has been somewhat optimized to make better profit of the DSD format. We will probably know better when we have the full announcement of the upgrade program.

I am not on the market for buying a new piece of HW by the way. I am just trying to optimize what I have at close to no cost. And using this feature seems a way to do so ; it certainly is not a purist way of doing things, but if it produces more airy music, in the same way Devialet AIR would do if it was working properly, I wouldn't care.

If you have the opportunity to test on your systems, I would be interested to read your experience.

[Confused]

It is interesting to consider what the difference is between upsampling via something like JRiver / HQPlayer, and via the 'hardware' option of the dCS. One difference is clear, about an additional £14000 for the dCS upsampler. Plus, the dCS utilises a 'master clock' which is about £10000. The dCS rig was clearly better with the master clock, it works fine without it, but sounded much better with.

So what does the £14k upsampler do that a decently powered PC with HQPlayer can't? There is stuff the dCS does such as galvanic isolation of the network, and so on. But in terms of the upsampling, computing power, software, I do not know.

I did wonder after listening to the dCS performing it's DSD upsampling tricks, how much of the improvement is 'real' and how much is 'created' by the up-sampling / down-sampling process. From what I heard, I would say it is doing something very real and impressive. However, I would need to spend a lot more time listening to the thing to be sure. Is the dSC doing something say HQPlayer can't? I suspect it is, although I have no hard facts, I guess I am thinking that for the price it should be doing something very special!

One point to note SwissBear, the dCS demo I had was with a good old fashioned D800 (not a D900 / O'dA), and yes it did sound stunning, I am just not sure exactly why! The performance of the dCS with DSD is in my head now, this is why DSD up-sampling is now on my (very long!) 'to do' list.

[MIKE]

Well, I also cannot believe that the conversion (DSD) itself, without changing the "starting material" can significantly improve the sound quality (unless DAC is technicaly better prepared to convert DSD signal).

Taking the opportunity... At SwissBear's printsereen I've just seen "audio device" settings: "Devialet USB audio 2.0 (core audio)". I have several other options (WASAPI,ASIO, etc) and personally I use WASAPI (without a special reason).

Do you recommend any specific setting?

[SwissBear]

I agree with Confused. It's a lossy process so you may actually like the character of the added distortion or the different filters used. I also think that the real advantages of DSD upsampling won't really show up unless using much higher DSD bit rates, higher than DSD64 and excellent upsampling algorithms. I'm no fan of JRiver BTW but would trust HQPlayer based on other users' experiences. Best would probably be a DAC that supports native DSD input, like the T+A DAC 8 (up to DSD512)

http://www.thewelltemperedcomputer.com/KB/DSD.htm

176/24 PCM and DSD64 are about the same resolution, they just have different distortions. Thus it seems a matter of preference which one is "better". However, converting between them is not such a great idea as the mismatch retains the worst aspects of PCM (smeared transients from the filters) and DSD64 (high frequency noise that starts at 25 kHz). DSD128 does not seem to have the problem with high frequency noise that DSD64 has, so this tradeoff seems moot, at least on my system.

Tony Lauck

Hi Antoine,

Seems that I forgot to thank you for the two references you gave in answer to my question.
Many thanks to you

[Antoine]

You're very welcome SwissBear and you did thank me earlier, maybe not for the links but that's allright of course!