There is old discussion on this. Stellar Gain Cell DAC different volume with different inputs
I notice the difference when I got the SGCD years ago.
So, I test it again today. Using a old Sony DVD player, digital coax to SGCD IN6, and Analog RCA to SGCD IN2. Set SGCD vol at about 10 for IN6 (digital), need about 13 for IN2 (analog) to roughly match the vol.