1st, welcome to the shack!
2nd, your home sound system sound awesome!
As far as impedance from system to system, you can get the impedance you want by being creative with wiring.
I'm assuming you know this with your background in electronics.
If you have 8 - 8 ohm speakers and you wish them to equal 8 ohms you can wire 4 groups of 2 in parallel, then wire 2 groups of those in series and end up with 2 - 8 ohm systems or 1 - 8 ohm system.
I may have the description wrong but either way, it can be done with as many speakers as you want.
I'm not big in audio systems so I may be way off base here adn in that case someone will offer useful info soon.
