I am using Volumio/Raspi as Streamer for DIGI out (Hifiberry) for my active LS. Is there any possibility to use a DAC for (almost) lossless Volume Control in Volumio? Fiddling around with the plastic Hypex remote and the volumio app is not a decent solution…
Well, I guess the problem is the DIGI out. DAC Volume Control is normal. But for analog outputs. I tried a Hifiberry DAC with Digi In/Out ports. Complete fail. Anyone using Dac, Vol Control and DIGI out?
I didn’t believe the difference would be noticeabe (or that my ears would notice) until I replaced my HifiBerry hat with a very affordable Topping D10S, but the improvement was obvious and significant.
Okay. I still don’t.fully understand. The USB Dac would be working as the port has a mixer that can be controlled by Volumio? If that is the case why do I need an additional DAC as I convert in the Hypex Module anyway? Would be an USB Coax/SPDif adapter suitable?
the S/PDIF is a very old standard protocol, it does not allow to send values and/or commands for volume control to the receiver side.
If the Bluesound Node has volume control capabilities on the S/PDIF interface, it means the output stream is sent already attenuated to the receiver. Thus, it is a SW volume control, not an hardware one. You can obtain the very same result enabling SW volume control on Volumio.
I’d like to elaborate a bit more on what I claimed before, with a high-level explanation on how HW volume control works
When using a I2S DAC with Hardware volume control
** the audio stream is sent “as-it-is” to the DAC via I2S interface, so bit-perfect / full-scale at 100%
** the volume value is sent by the linux driver via I2C interface to the DAC, and the DAC makes use of this value to adjust the level of the analog output ath the very end of the signal chain
When using a USB DAC with Hardware volume control
** USB is a universal interface, it can be used for different things, also simultaneously
** the audio stream is sent “as-it-is” to the DAC via UAC protocol, so bit-perfect / full-scale at 100%
** the volume value is sent by the linux driver to the DAC via HID or similar protocols, and the DAC makes use of this value to adjust the level of the analog output at the very end of the signal chain
When using a S/PDIF interface
** S/PDIF is a very old standard protocol, with well defined structure for the data.
** The S/PDIF protocol does not have the volume/attenuation information in the data structure
** It’s not possible to send the volume value to the receiver DAC, to be used for HW volume control as done for I2S and USB.
** if it’s possibile to have volume control on the Bluesound Node connected via S/PDIF, it means the audio stream is sent attenuated (so it’s manipulated, not bit-perfect) to the DAC, because it’s not possible to do otherwise.