Volume control when playing native DSD files

[raduval]

Hello guys,
My system is comprised of an RME ADI-2 DAC, Hegel H20 power amp and Spendor D7 speakers. I am presently playing my CD library from a USB drive attached to my laptop and streaming Qobuz from the same laptop, connected by USB to the DAC.
The problem is that, if I want to play DSD files in native format, I would not have any volume control, according to the DAC manual. DoP would work, but DoP is not DSD native. I listened to some DSD albums in native format on another system and DSD sounds better than my PCM files from CD or Qobuz.
The question is: Do I really need an analog preamplifier in order to play DSD files in native format, or is there a workaround this whole issue?
Your help in this matter would be highly appreciated.
Thank you.

 

[RayDunzl]

Do I really need an analog preamplifier in order to play DSD files in native format,

I'm going to say "yes".

Although, I don't see why the output voltage of a DSD decoder could not be varied for volume control before the analog output stage. Maybe it's an issue with SNR.

And maybe someone else has a better answer.

---

There may be professional solutions I don't know about.

https://www.soundonsound.com/sound-advice/q-can-i-record-mix-and-master-dsd

 

[PaulD]

The question is: Do I really need an analog preamplifier in order to play DSD files in native format, or is there a workaround this whole issue?
Your help in this matter would be highly appreciated.
Thank you.

A DSD stream cannot be modified at all, so you need a preamp if you want to remain in DSD land. If you want to modify it, then it must be converted to PCM, even for volume change (amplitude multiplication).

I would suggest that DSD is unnecessary and it's full of audiophile BS. High resolution PCM is at least as good, and without the ultrasonic noise-shaping issues, see https://archimago.blogspot.com/2013/04/musings-on-sacd-dsd-audio.html

DSD to PCM conversion is completely transparent, see https://archimago.blogspot.com/2015/04/analysis-dsd-decoders-2015-windows-mac.html So if you don't mind going to PCM then you can use a digital volume control.

 

[mansr]

I don't see why the output voltage of a DSD decoder could not be varied for volume control before the analog output stage. Maybe it's a issue with SNR.

That could be done by varying the reference voltage of the DAC chip if it has such an input, some do and some don't. However, the chip is probably optimised for a fairly narrow range, and performance may suffer if it is lowered too much (the datasheets are sketchy on this topic). A variable-gain output buffer accomplishes effectively the same thing and likely gives better results.

 

[Vincent Kars]

DoP is not DSD native.

Are you sure?

USB audio supports PCM only.
DoP is a trick to fool USB in transmitting pure DSD but it looks like PCM
http://www.thewelltemperedcomputer.com/KB/DOP.htm

The RME handles DoP on any input and indeed could play DSD direct
https://www.archiv.rme-audio.de/download/adi2dac_e.pdf

You need something like this for pure DSD: https://www.bax-shop.nl/studio-monitor-controller/tc-electronic

 

[mansr]

USB audio supports PCM only.

That's not entirely true. Although the USB Audio Class specification does not include DSD, many DACs support it using vendor-specific extensions. That said, DoP is no less "native" than any other way of transporting DSD samples. It has some overhead which can limit the DSD sample rate, but that's it.

 

[Vincent Kars]

many DACs support it using vendor-specific extensions.

That is new to me.
Does this means they have to supply a third party audio driver?

 

[mansr]

That is new to me.
Does this means they have to supply a third party audio driver?

The Linux/ALSA audio class driver supports the common encodings. I believe Mac and Windows don't support DSD at all even at the API level, so third-party systems (ASIO or whatever) are required there.

 

[Kal Rubinson]

I'm going to say "yes".

Although, I don't see why the output voltage of a DSD decoder could not be varied for volume control before the analog output stage. Maybe it's an issue with SNR.

It seems that the OP does need an analog VC but there are other DACs, such as the exaSound that allows VC with DSD playback.

 

[kmplng]

Perhaps @MC_RME could help here.

 

[MC_RME]

I try. As mentioned DoP is native DSD, the OP got confused with the two DSD playback modes of the ADI-2 DAC, Direct (no volume control) and 'normal' (the DAC chip converts DSD to PCM to be able to use volume control. Conversion and volume control happen directly in the DAC chip, while in PCM mode volume control is done by RME in the FPGA).

For many years most DACs used that internal conversion to PCM without telling the user. DACs with ESS chips have a digital volume control that claims to not use PCM conversion. The technique behind it is not disclosed by ESS, all we hear is third party wisdom about it, so pardon me to be sceptical.

Regarding USB: indeed doesn't support DSD. DoP is a clever way to circumvent this restriction. Popular by the many DACs using an XMOS USB chip is a different, but basically identical workaround. Again PCM bits are used to transfer DSD, but in a so called Alternate Setting. Class Compliant devices can have several Alternate Settings, thus offering different modes (max sample rate, amount of channels and bit resolution). An operating system will only use the first Alternate Setting by default. The XMOS drivers are able to activate that other mode and then can transfer DSD via 32 bit PCM. The advantage is simlar to DoP: as this mode is hidden and normally not activated, the user will not have a blast of full level white noise when playing DSD via PCM.

 

[mansr]

DACs with ESS chips have a digital volume control that claims to not use PCM conversion. The technique behind it is not disclosed by ESS, all we hear is third party wisdom about it, so pardon me to be sceptical.

As I've understood it, ESS DACs resample everything, including DSD, to some (high) internal rate, then send it through their "Hyperstream" modulator. If they claim not to do a PCM conversion, they probably mean they don't reduce the sample rate to something typical of PCM distribution formats. They're not alone in using that little marketing trick.

Since it is mathematically impossible to do anything at all to a DSD stream without going through a modulator, anyone implying otherwise is obviously bending the truth.

 

[Daverz]

As already mentioned, DoP is native DSD, just using a clever "packing" method.

My main problem with DSD is the DSF format, which uses ID3 tags instead of the more flexible Ogg Vorbis tags. Also you get a little pop noise at the end of each file.

 

[A800]

I can recommend the Behringer Monitor 1.