I have avoided enabling the volume control, because I use a pre-amp with a a DAC, (currently fed by an HDMI - SPDIF converter), and the software option warns of degrading the sound quality.
I have had a couple of thoughts. If the volume control is disabled, could it be removed from the interface?
If someone has a 24 bit DAC and is playing 16 bit sources, a simple stepped volume control with no degradation can be achieved by outputting at 24 bits and shifting the bits in the samples down by up to 8 bits (and padding with zeros). (Obviously when applied to 24 bit sources, there will be a progressive degradation down to 16 bit quality.) Such a system should really displayed in dB rather than percent.
The current software volume control works by scaling the output PCM stream, presumably by multiplication.
The advantage is a smooth volume control, but the disadvantages are processing power and the possibility of rounding errors.
If you were to shift all the bits of the stream by one place and set the most significant bit to zero, then you will get 6dB (if my maths is correct) attenuation, with no rounding errors (if the input is 16 bit and the output 24 bit) and no processor overhead.
My request is an extra option that works like this, and also displays the attenuation in dB (0dB, -6dB,-12dB, -18dB…)
The steps are that large that I would consider it useful as an attenuator for answering the phone for example, rather than for precise adjustment.