Axiom Home Page Forums General Discussion Technical Questions Speaker switches/selectors

So I now have 4 pairs of speakers in my stereo/music system (still not a fan of 5.1 music), really needing a switch box so I can do a better job of comparing.

Most of the commonly available speaker selectors seem to include "impedence control", along with an associated power limit and apparent loss of volume. This seems something like I don't want, but I don't know enough to make an intelligent decision. So...

1. What is this "impedence control" ? Transformer, resistors, something else ?

2. What is the purpose/function of this impedence control - is it just to stop someone from connecting 4 or 8 speakers in parallel and complaining when their amps don't like the resulting 1-2 ohm impedence, or is it something more nuanced intended to prevent momentary opens or transient parallels from damaging the amp ?

I'm going to be connecting 1 pair of speakers at a time, wondering if I need to look for "good impedence control" or avoid it like the plague.

Thanks !