Originally Posted by kannibul

One thing you didn't mention is that with solid state amplifiers (99.999% of car audio amps, unless you get tube...) can run with higher impedances (ohms), they just don't put out as much power.

So, if you have 8 ohm door speakers, and your amp is rated for 100w @ 4ohm, you'll probably get about 60-70w at 8ohm.

The important thing to remember is to not go BELOW what the amp can handle - run a 2ohm load on a 4ohm amp. That will make your amp unhappy, and could burn it up (overload)...