I have a set of Infinity Kappa 60.7cs for the front of my car and I am in need of a solid set of 6x9's to pair them with in the back. The Alpine PDX-4.100 will be powering them and is rated at 100 RMSx4 at 2 or 4 ohms so I'm assuming I can choose a set of 4 ohm 6x9's even though the 60.7cs' are...