I use the 2 wired digital inputs on my DS (RCA & XLR) for a DAB tuner and an Airplay input (with adaptors to convert the optical digital output from an Apple TV to XLR). The Airplay input (XLR) is permanently active to allow immediate streaming from phones, iPad etc but I only switch the DAB tuner on when I wish to listen to the radio.
A couple of days ago while streaming music through the Bridge I noticed I’d forgotten to switch off the tuner. When I did I noticed an improvement in SQ - not massive just slightly clearer sound.
I remember years ago when dealing with multiple analogue inputs to a preamp it was advised to leave other sources ‘live’ and short the inputs to any unused inputs. The suggestion (fact?) was that open-circuit and unterminated inputs could act as aerials and thus feed RF signals into the preamp so increasing the noise in the preamp.
Could there be a similar effect with the wired digital inputs to the DS?