Not sure if I’m answering your question but here’s my 2 cents... Gain is an analog stage prior to the ADC and Volume is digital prior to the DAC. I’ve always kept Vol at 100, but it’s simply DSP digital levels, so having it at 100% or 80% or 60% etc. shouldn’t make a sonic difference. I suppose it would lower the signal to the DAC and this also lowers the signal to noise ratio but probably not audible within reason. Digital volume control also tends to maintain more accurate channel balance than analog. Levels-wise in the Puffin the most important thing is to not set gain too high, otherwise the ADC will start clipping. Volume is a second best option to then match levels with other sources in your system. Or in a very simple system, if your Puffin is going straight to a power amp or powered speakers, you can use Volume as your volume control and shouldn’t feel like you’re losing any sound quality no matter where you set it.