How do you reliably ABX equipment that needs to be disconnected, and how can TOS #8 be satisfied in such situations? Options

[BearcatSandor]

(I was not sure where to put this. My emphasis is really on the testing methodology, not TOS #8 so i decided this would be the best area to put it in)

I'm still new here and trying to learn about proper ABXing and how to avoid the threat of a dreaded TOS 8 hammer (unsuccessfully it seems). I was asked about whether i had done an ABX test between 2 amplifiers. That got me thinking about how one would be able to do that in the first place in their own home.

Suppose i am ABXing a similar amplifier against the one i already have. My system is: Sound card ---> interconnects ---> amplifier (2 channel/1 input) ---> speaker cable ----> speakers
New amp would be the same: Soundcard ---> interconnects ---> amplifier (2 channel/1 input) ---> speaker cable ----> speakers
(a third one is needed? How does that work with hardware?)

To switch between the amps my assistant would need to move the interconnects back and forth between amps and the sound card outputs. That involves making sure that the amp 1 is shut down, removing the cables from amp 1 and plugging them into amp 2 and turning on amp 2. There would be significant lag in doing so, wouldn't there? The same problem would be there for cable ABXing as well.

Doesn't lag play a part in the accuracy of these tests?

How do you folks satisfy an ABX request in such a situation? Do you commonly have some sort of switching device in your home? How would i provide a sample for the community as outlined in TOS #8 (making it unsatisfiable)? Provide duplicates of the system used?

I looked around the site for information on how to ABX components but what i found seemed to relate to sound files and not hardware.

Could you folks help me understand this?

Thanks