Did you wire both speakers into the converter, or just one?
I wired both rear speakers to the line level converter. You want to do that because some studios will mix the low frequency signals into both channels but will run them out of phase. If you have only 1 speakers connected to the line level converter, it will cause your sub to sound like - "wobble wobble wobble..." because it's only getting half of the total low freq signal... it's safe just to connect both speakers into the 2 channel line level converter, then run the 2 outs into your amp, and let the amp mix them to a single signal out to your sub(s).
What is the remote wire?
Amps have a wire which (usually) accepts a low current 0->12volt hold that controls the main power to the amp.
You usually wire it up to the ignition switch which will ultimately turn the amp on/off when you start/stop the car.
It's a way to not drain your battery by leaving your amp on when you get out of your car at night
The hummer has a VERY great fuse which goes high (12 volts) when you turn on your ignition. Again, I bought that fuse link (thingy) at pep boys [make sure you get the 'mini' fuse]. It's a piece of cake to run the remote wire right down and through the panels on the driver side to the back of the truck.
The really nice thing about the hummers are how the panels are clipped on!! Very easy to pop off, no crappy plastic clips [like most foreign cars]...