Integrated as volume cntrl vs DSD volume

I have a Sonus Faber Musica integrated amp & DIrect Stream DAC. I had been using these with the Musica vol at max & controlling the volume with the DSD. I was thinking that, essentially the volume pot on the Musica would be out of the ckt & the DSD output would be driving the power amp directly. I have since changed to setting the DSD to 100 & controlling the volume with the Musica. The result is that it sounds much better. I don’t have the schematic for the Musica, so I don’t know how the higher input signal is making a difference in the sound. Any thoughts on this?
Thanks , Kev

You raised the Signal to noise ratio of the signal path.