This is probably a dumb question but here goes.

I have a subwoofer that I want to install in my QC. Unfortunately, it is rated 8ohms. My amp can handle 4 or 2 ohm loads. The speaker is a single voice coil. Is there any way I can convert it to 4 ohms? Can I wire a 4 ohm resistor in parallel?

 

The sub will work fine with the amp, it just wont get as loud since the resistance is 8Ohm instead of 4 (the sub will "see" about half the power).