1. No
2. Yes
3. No
First, I want to declare my bias that I love Chord DACs so I (unreasonably and irrationally) worship every word the Chord DAC designer Rob Watts says on Head-Fi.
According to my understanding of what he’s saying, whether digital volume controls are transparent are dependent on:
1) Low-level linearity of the DAC
2) Algorithm of digital volume attenuation (which almost everyone uses at 64-bit anyway)
3) Dithering/noise-shaping algorithm to reduce the 64-bit volume reduced signal to 24/32-bit for the DAC (except you can’t really noise-shape without upsampling first)
If all these digital computational/performance issues are achieved, digital volume control should be more transparent than analog. As a result, everything is system dependent.
4) DACs and analog preamps can have channel imbalance issues which are dependent on designs and hardware
As a result, with respect to the original set of questions:
1. Other than HQPlayer with it’s LNS15 filter, I’m not aware of any software that noise shapes an upsampled signal after volume reduction instead of dithering. in fact, I don’t use HQPlayer so I don’t even know if HQPlayer does that. I presume it does.
2. Many DACs have low-level linearity issues. This is why often they have an analog volume attenuation to avoid this problem.
3. Analog preamplifiers have it’s own issues with transparency and distortions.
4. If one is using a digitally transparent volume attenuation within a DAC, it is then important to figure out which analog preamp volume setting offers the lowest distortions and closest channel balance for optimal sound.
Moreover, people might prefer specific euphonic distortions introduced by imperfect digital volume control or analog volume control. So “accurate” volume attenuation is not always the ultimate goal.
That said, my take often is that audio is a hobby so people should just enjoy their music so whatever setting they love the most it’s the best setting.
