Got the two Type-X subwoofers installed last night, wired it exactly as shown in the Owner's Manual for a dual subwoofer series/parallel configuration. One plays fine, the other doesn't play at all. Alpine uses this crazy ass jumper design in which you use blade style jumpers to select "series" or "parallel" on each subwoofer. I am thinking their instructions are wrong, as they have turned a simple concept into rocket science. I gave up and went to bed before troubleshooting.
When I get home I am going to measure the DC resistance at the amplifier terminals and start troubleshooting from there. I'll probably end up having to pull each subwoofer and find out exactly which VC terminals these jumper blades are interfacing with and wire accordingly, ignoring Alpine's preprinted instructions. It's frustrating because they have overcomplicated the process, and even more so because I have to take the entire amp rack apart to get the subwoofers out.