• Aces
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Topic: Is it possible to get the headphone amp to function with dsd direct?

Hi New owner of a ADI 2 DAC here, just wondering is it possible to get the headphone amp working when in DSD direct mode, i know that the reason it's disabled is because of no volume control in the dac but as i use software volume control is there anyway to enable the amp, maybe a optional firmware update or something?

Reason i ask is because i software upsample all my music to either PCM 7xx or DSD256with HQplayer, i do find that the SQ does increase when sending upsampled DSD256/PCM768, and for the skeptics yes it does measure better this way

Measurements: https://audiophilestyle.com/forums/topi … ent=926151

2 Reply by bejoro (edited by bejoro 2019-06-03 12:03:16)

  • bejoro
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Re: Is it possible to get the headphone amp to function with dsd direct?

I have also tested PCM upsampling with ADI-2 PRO FS in detail. It sounds differently because of different or disabled digital filters. I do not like it, especially for 44/16, but that's a matter of taste.

I also tested PCM to DSD conversion thoroughly. ADI-2 PRO FS in Direct DSD mode with pre-amp for volume control and in volume controlled DSD, which is overall technically a PCM/DSD/PCM conversion. Unfortunately there had been no improvements on my reference system, on the contrary. I would not recommend it.

It is technically impossible to provide a digital volume control with DSD. You always have to convert DSD to PCM first if you want digital volume control.

PCM to DSD or DSD to PCM conversion is always a lossy conversion. There is no mathematically lossless conversion between the two formats. There are very high sofisticated and high demanding algorithms necessary to get an almost perfect conversion.

PCM upsampling/downsampling is lossless if done correctly.

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  • Aces
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Re: Is it possible to get the headphone amp to function with dsd direct?

bejoro wrote:

I have also tested PCM upsampling with ADI-2 PRO FS in detail. It sounds differently because of different or disabled digital filters. I do not like it, especially for 44/16, but that's a matter of taste.

I also tested PCM to DSD conversion thoroughly. ADI-2 PRO FS in Direct DSD mode with pre-amp for volume control and in volume controlled DSD, which is overall technically a PCM/DSD/PCM conversion. Unfortunately there had been no improvements on my reference system, on the contrary. I would not recommend it.

It is technically impossible to provide a digital volume control with DSD. You always have to convert DSD to PCM first if you want digital volume control.

PCM to DSD or DSD to PCM conversion is always a lossy conversion. There is no mathematically lossless conversion between the two formats. There are very high sofisticated and high demanding algorithms necessary to get an almost perfect conversion.

PCM upsampling/downsampling is lossless if done correctly.

True that PCM to DSD is lossy but doesn't SDM DACs also use almost exactly this same method? Upsampling to higher sample rates with less bitdepth,and using noise shaping techniques to get usable bits out of it?
Using DSD direct then with HQplayer is basically replacing the fir, and modulator in the DAC chip with a software based one which does not have the same resource constraints as the built-in one.

idk I just hear more depth when using DSD direct with hqplayer, and my HD800 can't really explain why, have you at least tried HQplayer with DSD direct there's a trial period if your interested?

4 Reply by bejoro (edited by bejoro 2019-06-03 17:24:54)

  • bejoro
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Re: Is it possible to get the headphone amp to function with dsd direct?

The imagination of more depth lies in the loss of impulse response (less dynamic). Because of less prominent sound events the acoustic perception creates the imagination of a deeper sound stage, or better said, the sound stage seems to be further away. But it is still a loss of information (for example artistic expression) and does not correspond to the original recording.

A similar effect occurs with the usage of a battery as a power supply, but less signifcant. That's another story.

But if you prefer the imagination of a further away projected sound stage, go for it. But you lose more than you gain. With headphones, especially with a HD800 it might be desireable. With a reference speaker setup the loss of information is much clearer because of far better localisation (with very good recordings, of course).

My knowledge bases on detailed studies of human acoustic perception (psychoacoustics). Many, many listening tests with different setups and different persons for several months.

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  • Aces
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Re: Is it possible to get the headphone amp to function with dsd direct?

bejoro wrote:

The imagination of more depth lies in the loss of impulse response (less dynamic). Because of less prominent sound events the acoustic perception creates the imagination of a deeper sound stage, or better said, the sound stage seems to be further away. But it is still a loss of information (for example artistic expression) and does not correspond to the original recording.

A similar effect occurs with the usage of a battery as a power supply, but less signifcant. That's another story.

But if you prefer the imagination of a further away projected sound stage, go for it. But you lose more than you gain. With headphones, especially with a HD800 it might be desireable. With a reference speaker setup the loss of information is much clearer because of far better localisation (with very good recordings, of course).

My knowledge bases on detailed studies of human acoustic perception (psychoacoustics). Many, many listening tests with different setups and different persons for several months.

Hmm I see I didn't know that the increased soundstage was actually loss of information, always thought it meant better SQ.

But then I wonder why replacing the in built modulator with a software based one DSD direct etc, gives loss of information when the one in the player has more resources to work with, isn't more better etc?

Though to be honest I really like the tonality of the appodizing/closed-form filters when only upsampling PCM to 768khz using HQplayer, I view it as extra filters to change tonality just like the inbuilt filters in the AKM4490 that the rme has.

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Re: Is it possible to get the headphone amp to function with dsd direct?

Hi @bejoro  all that's very interesting. Can I read (in English) more about what you write and about the studies. I will be more than happy if you drop me a link.

Regards, Siemak.

  • Aces
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Re: Is it possible to get the headphone amp to function with dsd direct?

The imagination of more depth lies in the loss of impulse response

Is this the same thing as impulse response in filter pre/post ringing etc?

8 Reply by bejoro (edited by bejoro 2019-06-04 07:38:22)

  • bejoro
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Re: Is it possible to get the headphone amp to function with dsd direct?

Siemak wrote:

Hi @bejoro  all that's very interesting. Can I read (in English) more about what you write and about the studies. I will be more than happy if you drop me a link.

Regards, Siemak.

It was one part of my own research, included in a research contract of a manufacturer.
Unfortunately the papers are not publicly available.

@Aces
The expansion of the virtual soundstage can be an indication of an improvement. In this case it is not. The subject is too complex to discuss it here in detail. Just try to be critical and always "look" for unwanted side effects. But if you like it and do not miss anything, stay with it and be happy. wink

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