I've applied shorting plugs to my VAC Ren Sig II's unused inputs, and I sure believe it made it quieter. Spent all of a $1 a piece off of Ebay, just as bdp24 notes above, so I haven't sweated it much to make dead sure of it...
RCA or XLR iInput Shorting Plugs or Pins
Looking for opinions on the routine use shorting or non shorting plugs, pins or caps on unused preamplifier or amplifier inputs. Does it really lower noise if inputs are not selected? Shorting vs Non shorting? Why are some manufacturers opposed to shorting plugs for routine use? Is there as much merit for XLR shorting pins as RCA shorting plugs? Thank you for your advice and opinions!