If it’s not used why switch to it?? And negative affect to what??
I believe it has already been clearly established as FACT [on the basis of this and other related (shorting inputs) threads here on Audiogon], that shorting unused inputs **can only be advantageous, even if only theoretical** (electrical theory).
In other words, there can be no disadvantage in shorting an unused input from an electrical perspective.
So, in consideration of the aforementioned....
I would switch to an unused and un-shorted input to glean whatever noise I can, in order to subsequently switch to the same input *when shorted*, in an attempt to then determine if the noise - from that input -has been reduced.
So, in consideration of the aforementioned....
The negative effect *can* be "input cross-talk" that the amplifier is unable to filter.
Meaning, while the amplifier is amplifying the signal it is receiving from its currently in-use input, it is also amplifying the un-wanted noise resulting from the unused input(s).
So, in consideration of the aforementioned....
The benefit is that while listening to the in-use input, the overall systems noise floor has been lowered. In this context, "lowered" means "reduced by any decibel level greater than zero".
So, in consideration of the aforementioned....
Is there a shorting plug for USB B input?