Is it possible to make a lossless volume control?
In my opinion is to attennuate in 6db steps.
Is it possible it can be an option in the future?
you can’t have a lossless volume control, unless your DAC supports a hardware mixer.
If you play with volume levels, your altering the source signal. By altering the source signal you loose lossless (read bit perfect).
Since there will always be some kind of noise in a system. This noise is not part of the bitperfect signal. By lowering the volume, you can’t control the noise level. In the end S/N ratio will become high as “N” is pretty static.
An easy way to test is:
Set the SW volume control too 100% and you amplifier to 20%. Remember the level of volume it generates on your speakers.
Now lover the SW volume control to 10% and crank up the amplifier to get the same volume output. You will here the contribution of noise very clear.
For those who like numbers.
assume we have a noise level in our setup of 1%, With the SW Volume set to 100%, the partition of noise is in total 1/100 * 100 = 1%
Lowering the SW volume to 10% => 1/10 * 100 = 10%
Yes thats right. Analog volume controls have loss.
Software based digital volume control (DAC) also have loss. Even i high calculation rate because of we like to have the number dB.
But if you attenuate digital audio by 6db you half (exactly) the sound and its equal to shift the value one place.
If you have 24-bit data and 32-bit dac you can attenuate/shift signal by 8 bit before cutting signal. 8 bit is 6x8=48 db. Enough for me for lising sound level. I am not listing to music so low. If I will listing quiet I can change to DAC hardware dac.
if only ALLO wouldn’t be so super worse with support - they did have a valuable hardware with their relay volume control - but no response to support v3 of Volumio