I just installed, in my 2006 Chevrolet Equinox, a Kenwood DDX512 head unit, 2 alpine type e subs, and an alpine mrp-m500 amp. The head unit is working fine. The subs are working, but they are not loud at all. I have messed with all different settings and can find nothing to fix the problem. The one thing that seems like it could make a difference is a setting called "Sub Woofer" and it is set to off but there is no way to turn it on. Any help is greatly appreciated.