You can always split a source into two outputs but you should never try to combine sources into one input. Use a properly wired switch with a null point in its center position to select between sources. The unused source should always be powered down when not in use.

Assuming the RCA splitter is decent quality, you should loose -3dB of signal strength by splitting the signal between two outputs. Unfortunately, most store bought splitters are not very high quality. Look around for the best you can find and realize fancy outer appearance doesn't guarantee good quality signal transfer. If you know how to solder, make up your own splitters with Switchcraft parts.

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You can always split a source into two outputs but you should never try to combine sources into one input. Use a properly wired switch with a null point in its center position to select between sources. The unused source should always be powered down when not in use.

Assuming the RCA splitter is decent quality, you should loose -3dB of signal strength by splitting the signal between two outputs. Unfortunately, most store bought splitters are not very high quality. Look around for the best you can find and realize fancy outer appearance doesn't guarantee good quality signal transfer. If you know how to solder, make up your own splitters with Switchcraft parts.

Your first paragraph is correct. One can split outputs.
Combining multiple inputs together into one is probably not a good idea. The low output impedence of the second source would probably load down the signal of the first source.

As for your second paragraph, you are incorrect. You seem to still be having problems with the concepts of voltage source, current source and power transfer. In an RF environment (not audio) such as your antenna cable, using a splitter will split the signal strength in half (-3db) as you state.
In a voltage source interconnect as used in HiFi, combining loads will cause an increase in the load presented to the source but most likely because of the huge differences in source impedence and load impedence it will be a non issue.
The drop in signal will not be 3db and will most likely not even be unmeassureable. You seem to have some technical knowledge. Try some simple ohms law calculations using various source and load values and prove it to yourself.

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Try some simple ohms law calculations using various source and load values and prove it to yourself.

Awww, you want me to do math?! Cripes! Where's that calculator?

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In an RF environment (not audio) such as your antenna cable, using a splitter will split the signal strength in half (-3db)...

I have always accepted this on faith, but do not understand why that is. Is there a quick explanation that you can provide? (I've previously convinced myself that one can safely split outputs of an audio signal...)

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Try some simple ohms law calculations using various source and load values and prove it to yourself.

Awww, you want me to do math?! Cripes! Where's that calculator?

I know what you mean. I don't use a calculator much anymore either. After going through the math once, the revelation of the effect of ratios makes mental calculations easy.

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After going through the math once, the revelation of the effect of ratios makes mental calculations easy.

You took the words right out of my mouth.

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In an RF environment (not audio) such as your antenna cable, using a splitter will split the signal strength in half (-3db)...

I have always accepted this on faith, but do not understand why that is. Is there a quick explanation that you can provide? (I've previously convinced myself that one can safely split outputs of an audio signal...)

I think that my explanations are not so good despite my attempts. Maybe someone else can help?
Voltage source - low output impedence, high load impedence
Current source - high output impedence, low load impedence
Power transfer - equal source, interconnect and load impedence.

This is beyond the capabilities of my basic-college-physics brain! I can whip out Ohm's law and Kirchoff's loop/junction rule problems, though!

My minimal exposure has been fun so far. I'm always thinking "Oh, cool, so that's how that works". I think I secretly want to be an electrical engineer. I guess I'll have to settle for medical school.

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This is beyond the capabilities of my basic-college-physics brain! I can whip out Ohm's law and Kirchoff's loop/junction rule problems, though!

Come on people, quit making this complicated.
I know that word problems confuse many but work through it.
Nothing more difficult than multiplication and division.

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My minimal exposure has been fun so far. I'm always thinking "Oh, cool, so that's how that works". I think I secretly want to be an electrical engineer. I guess I'll have to settle for medical school.

At least in the medical field you will have the pharmacutical companies to tell you what to think.

Hahaha! Touche.

I wasn't clear. I understand the basic formula for audio range frequencies.

My question is why this is different for RF? It may be that there is a characteristic of RF that I don't know that makes the answer obvious if this tidbit is known.

Although this is a diversion from the initial question it is directly related and addresses a simpler version of the problem. For some time now, I've been using some Monster Cable splitters (solid construction-no wires) to feed my headphone amp. I'm breaking the "output OK, input no" rule, or so it would seem. Perhaps, owing to the way I use the set-up, the circumstances are different. One feed connects to an Analysis plus interconnect for an iPod - mini plug to RCA. The iPod is never connected when I'm using the other feed which is a conventional RCA interconnect to a CD player. I suppose, from your cautions that I should be experiencing some signal degradation at least when using the iPod as a source, and perhaps with either source. Maybe because I don't expect too much from the iPod, I've not been aware of anything audible. What kind of practical level problems have I set up for myself in this? I'm not too old to learn.

You probably won't have "level" problems unless one or both of the units stops working. You wouldn't connect two power amplifiers to the same speakers for the same reasons you don't want to connect two sources to the same input. If both are working at the same time, there is the possibility you can blow up the output stages of one or both devices. Think of negative feedback on steroids. More likely though, you will load down the signal from one unit with the additional output circuit impedance of the second even if the second is not powered up. This would result in frequency response errors. It is best to have a triple throw switch with a center null so the two devices can never see one another. This would be particularly helpful if there's any chance someone else might be operating your system.

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I wasn't clear. I understand the basic formula for audio range frequencies.

My question is why this is different for RF? It may be that there is a characteristic of RF that I don't know that makes the answer obvious if this tidbit is known.

The formulas are still the same for RF and audio frequencies. The big difference is the effect of reactive components at very high frequencies. As frequency goes up the effect of mainly cable and circuit capacitance becomes significant.

Quote>> "...If both are working at the same time,..."

Clearly, I wasn't clear. I'll try again. The purpose of the set-up was to provide music while I mess around on the net. That's what it is doing now with the iPod as the source. The CD player is off, but still connected. If I were listening to the CD player now, the iPod would be disconnected - at the mini plug end of the interconnect. The idea was to allow the convenience of providing music from either source - certainly not both sources simultaneously.

I don't hear any problems resulting from the connection to the powered down CD player now, and when I use the CD player I don't detect any problems resulting from the interconnect sitting idle waiting for the iPod to be connected. Do you suppose there are some and my ears are just so old that I'm impervious to them?

Got it this time.

Thanks, Cyclebrain!

Probably not enough to worry about if at all. It would depend on the source to input impedance of the pre amp. The danger of two interfacing sources is really the possibility of damage to one or both of the units when they are both powered up.

I realize that you weren't using both sources at the same time but I still insist that it is a bad idea.
You may not hear any difference or damage anything but there is no way that this setup can be a good thing.

I've no doubt that you're right, Cyclebrain. On principle I've always avoided that sort of thing, but switching interconnects on my little MF XCan V3 was so damned inconvenient that when I saw those little solid splitters in the Audio Advisor catalog, I went for them and gave it a try. I couldn't hear any difference, still can't. Chalk up a bit of slovenliness in a secondary system to plain laziness. Thanks for the advice.

I got mine at Audio Advisor if you still want to use them. [url=www.audioadvisor.com]

Go here link
Email Doug and tell him what you want. He can use one of many grades of wire and quality connector you may want, and make them. Get a quote and then look around some more.

Disclaimer: I am not affiliated in any way other being a satisfied customer of CatCable, and they can custom-make just about anything you can come up with at little or no extra charge other than normal material and labor charges.