What would happen if?

Oh go do it. I don't think that the second set of cables left attached to the amp changes any of the parameters of the amp at all. Think about it......

But, shorting is a REAL issue! What I have done when necessary is to tape the wires with spades so that the + and - wires are well away from each other and can't under any circumstances touch. Ditto for banana plugs if they are individual plugs (not two encased in plastic, seperated the proper space to match to many speaker and amp connectors).

Re the taping, hell I'm so anal about the shorting potential I tape all of my loose ends, spades, bananas, whatever, so they can't short if one or both were to come loose from the speakers or amps. Highly recommended!

FWIW.

I'm with Newbie on this one... just do it. it's temp anyhow.

You must have a completed circuit for electrons to move - conduct.

Connect and disconnect whatever, with the amp dead off. Once amp connections are made put whatever cables onto whatever speakers. Only one leg (one positive or one negative) of the cables not being listened to needs be disconnected to prevent any current flow into those 'off for now' speakers.... not both. Of course, insulating the exposed leg so it won't touch it's proposed binding post is important.

A balloon or tape, or a shoe or phone book... anything preventing conductivity will suffice.

Just 'member, power off the amp prior to making up and unmaking ANY connections to the speakers themselves.

As was said above about A/B ing, I'd shy away from instantaneously attemnpting that event. Given the power up and down safety measures you'll want to take, it's not viable anyhow. Just take notes instead.

I don't see any reason why you can't do that, and get reasonably valid results. Provided of course that, as many have said above, you make absolutely sure to avoid the possibility of a short circuit, and as long as connections are changed only with the power off.

The idea of disconnecting only one leg of one of the cables is not correct. It will invalidate your results because on the other polarity (positive or negative; the opposite polarity from the one that you disconnect the one leg from) you will have that polarity conducted in parallel through the corresponding legs of two cables. The current will take advantage of that and divide itself between both paths on that polarity, in inverse proportion to the resistance of each path.

I don't think that concerns about antenna effects and capacitive loading are likely to be relevant to the power amp/speaker interface, due to the extremely low output impedance that power amps have to have (well under one ohm usually), as well as the fairly low input impedance of the speakers themselves. The low impedances would load down any rf or emi that was picked up from the air (that's why speaker cables are usually not shielded, not to mention that the frequency of the interference would be far too high for the speakers to respond to). The added capacitance is likely to be have essentially zero effect because the resulting capacitive impedance (reactance) would be vastly higher than the output impedance of the power amp. It would be a completely different story with line level interconnects.

Regards,
-- Al

Wouldn't do it. Too many unkowns to say what would happen. You're essentially adding a capacitor across the amp's output. Depending on the capacitance the amp may not like it. However large or small, you're asking the amp to drive an additional needless capacitive load. At the least you're affecting frequency response somewhere. Likely that your evaluation of each cable would be scewed also because of the additional capacitance that wouldn't be there otherwise.

Cheers!

Robert
RSAD

Following up on my previous comments about capacitance, consider the following calculation:

Assume as a very rough ballpark that cable capacitance is 50 picofarads (pf) per foot, a typical number. Assume a 20 foot cable length. That gives a total capacitance of around 1000 pf.

The resulting capacitive reactance at 20,000 Hz (the worst case frequency within the audio band, in terms of the potential effects), based on 1/2piFC (pi = 3.14; F = frequency in Hertz, C = capacitance in farads, to get results in ohms), would be a capacitive reactance of around 8000 ohms.

With the output impedance of the amp likely to be well under 1 ohm, and the speaker input impedance likely to be 8 ohms or less, 8000 ohms of capacitive reactance is, in comparison, essentially infinite, and it would seem to the amp/speaker interface that the capacitance is not there.

Regards,
-- Al