Oppo: https://www.oppodigital.com.au/blogs/reviews-resources/15420449-using-your-oppo-as-a-pre-amplifier
For digital vs analogue volume control, I simply repeat the reference to the Sabre presentation (there is also a longer text by Sabre but I could not quickly find it). Can you hear imperfections at -135dB, and do you have source material that is this clean? Do not forget that analogue volume controls have their weakneses as well, like channel imbalance at lower levels. There are more important things to worry about.
For digital vs analogue volume control, I simply repeat the reference to the Sabre presentation (there is also a longer text by Sabre but I could not quickly find it). Can you hear imperfections at -135dB, and do you have source material that is this clean? Do not forget that analogue volume controls have their weakneses as well, like channel imbalance at lower levels. There are more important things to worry about.