RCA Shorting Plugs

Like many other threads on this forum that are essentially duplicative, I recently resurrected an older topic related to this subject.
https://forum.audiogon.com/discussions/rca-caps

Given the input (no pun intended) of Al and George (and others, thank you, btw) I will be giving this (shorting inputs) a try within a month or so. I’m hopeful to have the same or similar results to the OP, and agree that the noise floor is an important aspect to get under the best control possible (i.e. the lower the better).

@erik_squires 

Very true regarding the room acoustics, however, I can assure you noise from the system itself (and all systems emanate some noise) is easily distinguishable. That said, system noise to a certain degree is "manageable".

@almarg

In the related thread mentioned herein, I posted a question worthy (IMO) of your input (no pun intended) :) As that question has gone unanswered there, I thought I might pose the question here.

Might or should there be a theoretical or practical difference when using shorting plugs on an input dependent on the class of amplifier?

Reason I ask is that I’ve obtained and installed these:

https://www.amazon.com/Viborg-Audio-Stopper-Plated-Protector/dp/B017DH76VS/ref=sr_1_1?ie=UTF8&qi....

While I cannot detect a difference in the way my MF M6si (class B or A/B) noise floor emanates the slightest "hiss" or "sizzle" (no music source but volume cranked past 12) with or without the shorting plugs, I can detect a difference when I put them on the LFE input (class D) of my Golden Ear Triton Reference speakers.

Thanks, Al.

EDIT:

I'm aware of the difference in-so-far as the M6si I'm hearing the sound from the tweeter whereas in the T Refs the sound is from the woofer. So perhaps the shorting of inputs effects a particular frequency range more so than others?

@almarg 

I appreciate the rather prompt response on your part. Very prompt for that matter as I added an edit to my previous post. 

Given what you have just stated, might or should there be difference based on frequency? 

In the case of the M6si I'm hearing the sound from the tweeter, whereas in the T Refs the sound is from the woofer. 

May I get a consensus please on the merits or lack thereof of shorting a USB B input? Reason I ask is my amp has a USB(B)  DAC which I'm not using. If I switch to that input and raise volume to 12 or beyond there is, not surprisingly, some amount of noise at the speaker.

I've alread shorted my unused RCA unused inputs. I cannot seem to find (google search) USB B shorting plugs, and in fact certain articles appear to caution against shorting USB inputs.

Opinions and/or links to such a part appreciated.

Thanks.

Buy switching to an unused input your subjecting the input first active stage to an open circuit.
The simple fix is not to switch to it, if it’s not used.
By putting blanking/shorting plugs on the unused inputs doesn’t make the used inputs sound any better.

Hi George. To clarify, I'm not wanting or expecting the unused input to sound better. What I am expecting, however, is that by shorting an unused input, its potentially negative effect that it has (if not shorted) on a *used* input is minimized.

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?

@almarg

Thank you!!!! Trust me, I shall heed your advice.

This is pure BS, because if they’re not used they are not connected to any active amplification circuitry!!

True that an unused input is not connected to active amplification circuitry. However, it is somewhat irrelevant within the context and spirit of this thread, and as a reply to my statement that you were quoting: "shorting unused inputs **can only be advantageous, even if only theoretical** (electrical theory)."

The unused inputs could be close enough to active amplification circuitry, causing the unused input to contribute to the overall "noise floor" of the system. Granted, in a perfect world the amplifiers active input would be adequately shielded to prevent what I’ve described, but as you know, we certainly are not living in a perfect world.

This is why I indicated "shorting unused inputs CAN only be advantageous, even if only theoretical". I did NOT indicate it *necessarily is or always would be* advantageous.

Non shorting plugs prevent rf from getting inside the component.

I think what you mean to indicate here is that non shorting plugs *could* mitigate the effect of rf from getting inside the component; not prevent it. RF has a habit permeating audio related gear regardless of whatever is done to prevent it.