12-06-2019, 05:31 PM
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.
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.
