RCA Caps

Like the Cardas Caps they don't having to be shorting type caps to be effective. Cardas type caps are simple covers for unused input and output plugs. They should be placed over ALL input and output plugs for max benefit. Copper foil can be used in lieu of the real McCoy. 

I found the Aurora Tronics plugs in a 2015 ebay ad. It doesn't matter who makes them, as long as the hot center pin and outer ground are soldered together, to create the short. Anything less is merely cosmetic.

Sorry if this was covered earlier but why not just use caps to cover the unused plugs? I bought a set of 5 pairs gold plated caps for around $15. These are just "caps" with no pin inside.

Kalali, a shorting plug will have electrical effects, by lowering the input impedance of the unused input to essentially zero ohms. Low impedance circuit points are inherently less susceptible to pickup of electrical noise than high impedance circuit points, everything else being equal. Including pickup of noise that may even originate elsewhere within the same component, that may in turn find its way from the unused input path to the signal path that is being used, or to a circuit point (such as in the power supply) which can affect that signal path.

As was mentioned earlier, and despite some disagreement that was expressed, caps that do not short the input will do nothing other than perhaps reducing oxidation or corrosion of the ground shell that may occur over time, and keeping out a few dust particles.

Regards,
-- Al

https://www.ebay.com/p/8pcs-RCA-Cap-Protector-Dust-Proof-Brass-Gold-Plated-Shielding-Caps/1261404073...
That's what I using on my HT receiver unused inputs and remove the center pin for the unused outputs