I think the idea behind shorting plugs is that open ended inputs pick up stray rf interference and by shorting the inputs you shunt this to ground. Additionally, if left open the interference picked up can enter your active channels through cross-talk. Thus, there is a sound electrical engineering-based rational for shorting un-used inputs. EE's may argue that this is splitting hairs or going overboard with worrying about noise. I would say that perhaps it is more a matter of the resolution of your system (and I am an EE -- but I am also an audiophile, and no I don't believe in mysticism, voodoo, or snake oil in audio system tweaks that some accessory marketers try to sell us).
An example of real versus voodoo that I experienced comes to mind -- the livery cabs in my neighborhood have illegally powerful radios that interfered so badly with my stereo that I could clearly hear their conversations through it. I live six stories up. The only way to eliminate this interference was to put those magnetic rf elimination protectors around the cables between my amp and pre-amp, close to the amp side of the cables. Nothing else worked.
Now with the input plugs shorted I notice a drop in the noise floor. I only notice this effect in low level passages of music. However, I do wonder if the extraneous noise has an impact on things like signal transients that could have negatives effects on the timbral quality and imaging in the sound reproduction. Input shorting plugs are cheap -- for single ended inputs buy the cheap Radio Shack jobs and solder a wire between hot and ground; $5 and 1/2 hour and no worries from open ended inputs. I saw an ad for very expensive rhodium plated ones from a very high end cable manufacturer. Pshaw!!! Use that money towards a Koestu, or other great cartidge! Or use that money elsewhere in your system where it will make a difference. I can't say it enough; please, give me a break! Expensive rhodium plated rca shorters-- come on! Or rather, go ahead, buy them sucker.
For balanced inputs, contact the repair person at your local high end shop and ask him/her about it. If they don't carry them, they should be able to make them.
Whether equipment that is plugged in and turned off picks up rf and imposes noise is yet another question... I don't know the impedance of my components when they are shut off. I never bothered to think about it. My inclination is that it is not high enough to pick up rf. I may be wrong, though.
An example of real versus voodoo that I experienced comes to mind -- the livery cabs in my neighborhood have illegally powerful radios that interfered so badly with my stereo that I could clearly hear their conversations through it. I live six stories up. The only way to eliminate this interference was to put those magnetic rf elimination protectors around the cables between my amp and pre-amp, close to the amp side of the cables. Nothing else worked.
Now with the input plugs shorted I notice a drop in the noise floor. I only notice this effect in low level passages of music. However, I do wonder if the extraneous noise has an impact on things like signal transients that could have negatives effects on the timbral quality and imaging in the sound reproduction. Input shorting plugs are cheap -- for single ended inputs buy the cheap Radio Shack jobs and solder a wire between hot and ground; $5 and 1/2 hour and no worries from open ended inputs. I saw an ad for very expensive rhodium plated ones from a very high end cable manufacturer. Pshaw!!! Use that money towards a Koestu, or other great cartidge! Or use that money elsewhere in your system where it will make a difference. I can't say it enough; please, give me a break! Expensive rhodium plated rca shorters-- come on! Or rather, go ahead, buy them sucker.
For balanced inputs, contact the repair person at your local high end shop and ask him/her about it. If they don't carry them, they should be able to make them.
Whether equipment that is plugged in and turned off picks up rf and imposes noise is yet another question... I don't know the impedance of my components when they are shut off. I never bothered to think about it. My inclination is that it is not high enough to pick up rf. I may be wrong, though.