DSD and Hardware Volume Control

[TheOldPresbyope]

I have only a dozen or so DSD encoded tracks, and I don't plan on building a major collection of them, so this is an academic question.

The facts as I know them:

My Khadas Tone Board (ES9038Q2M DAC chip/XMOS microcontroller/USB interface) can play native DSD as well as DoP. The board supports hardware volume control for PCM but not for DSD or DoP. [1]

Tim says his Allo Katana board (same ES9038Q2M DAC chip/I2S interface and control) does support hardware volume control for DSD.

My question:

Is there anywhere a curated list of I2S DAC hats and USB DAC boards showing which do and which don't support hardware volume control in DSD playback?

What has been the experience of fellow moOde users?

Regards,
Kent

[1] It is commonly assumed that the KTB firmware either lacks the needed microcode or has a botched implementation. There have been a few firmware updates but none address this issue despite user pleas on the Khadas forum.

[Tim Curtis]

The general answer is that its not possible to apply DSP (volume, eq, etc) to native DSD bitstream format because of the way the format encodes the signal's amplitude as a varying density of 1-bit values (0 or 1). Thus to perform DSP on a bitstream it first must be converted to a format where the amplitude can be mathematically manipulated. 

IIRC, ESS Sabre DAC chips perform this conversion in the on-chip Asynchonous Sample Rate Converter (ASRC) component.

The Allo Katana and Audiophonics ESS 9028/38 based I2S DAC's both support Hardware volume control for DSD (DoP) by making use of the ASRC mode of the ESS chip.

I think a lot of ESS based USB DAC's also support hardware volume for DSD. I dunno what's going on with the USB Khadas board and why it apparently does not allow hardware volume for DSD(DoP). Very odd.

[TheOldPresbyope]

Yeah, I understand the theory. 

My problem is the practice. Vendors love to brag on their websites about the DAC chips they use and all the formats they support but are often short on details in their so-called technical specifications. 

Hence the question about a list. It's like the early days of the Raspberry Pi when users were compiling lists of WiFi adapters and which of their features (notably AP-mode) worked.

I can dream, can't I?

Regards,
Kent

[Tim Curtis]

Audio vendors short on details? Shocking, lol