Should be 2ohms. Are they 4ohm single voice coil? Go with a mono block class D amp. They're usually stable down to 1 or 2 ohms mono and run more efficently then a 2 channel class a/b. I personally like JBL as a budget choice, I know Curtis has had good luck with Hifonics. Ofcourse there's other brands that are as good and better but you'll be paying atleast 2 or 3x's as much.