In my experience, comparing the DS Sr.’s Bridge II input to the I2S input while the Bridge II remains installed is not a fair comparison. The fair comparison is the Bridge II versus I2S after the Bridge II has been removed. The Bridge II is inherently noisy, and many have concluded that the mere act of removing it improves the sound of the other DS inputs. Comparing the sound of the Bridge II versus I2S minus the Bridge II revealed a very clear winner in my system, and it wasn’t the Bridge II. YMMV.
BTW, I sold my Bridge II, then my DS Sr. and my Matrix, so I do not have a dog in this hunt. But I still remember how startling it was to hear the DS Sr. for the first time after removing the Bridge II, which input I had long since stop using. The improvement verged on a component-level upgrade. If you want to know how good the I2S input can sound, I think removing the Bridge II is one of the best things one can do. (And the frequent Bridge II for-sale offerings on this forum suggest that others have found preferred signal paths, as well.)