what is the ohm of my cassette/head unit in my 1997 f250? i just bought 4 new speakers that are 4 ohm.. my bro and i just installed 2 ohm speakers, he had a 4 ohm head unit, and the head unit screwed up..

depending on what the ohm is of my head unit, do i have to match ohms? run 4 with 4?

 

It's more to do with the current capabilities of the built in amplifiers. Pretty much all Automotive radios should run 4ohm. Using 2ohm doubles the amperage and the stock amplifiers can't handle the current and fry. Rule of thumb is automotive is 4ohm and home is 8ohm, if you use anything lower, you need to check the amplifier.

You can run 2ohm, but you will need another amplifier that is 2ohm stable.