I have a small setup I did just from a sub/enclosure i had sitting around and an amp that i took out from my audi.
The setup still has the OE subs playing, and this on top, i tuned the amp so this gets the deeper / lower bass notes better then the small ones behind the cover.
- Clarion XR2210 Amp
- Kicker 10" CVR
- Sealed Enclosure
Most setups doing it this way you need a line output converter, then run a double rca cable from line output to amp, but that clarion has one "built in" so to say, regardless same setup either way, just without the "built in" you wire in the line output and need the rcas then...
I have mine tapped into the wiring on the left panel in trunk, and the amp turns on if the radio/cd is on, if they are off its off.
Positive wire + fuse i have ran in the battery in trunk, ground is grounded under a bolt on the chassis in back, and rest wired in etc.
Heres some pics back when i was installing, i chose my amp location there since its easy access, and hidden, if i need to take out the spare or do something under that cover, i just lift it up off the velcro and put it to the side.