Do I need another amp for a sub-woofer?

[Alien Mantis]

My system doesn't rattle my whole car. One 10" is not really enough to be annoying. My bass is nicely balanced in the mix. Any more bass, and it would overpower the rest of the mix.

I am running a very conservative, low-watt system.
I have a Pioneer HU that feeds 15 watts to Pioneer 6.5" coaxials crossed over at 125hz.
My bass is one 10" Alpine Type-R sub, in a ported box powered by a Pioneer class D monoblock at 400watts RMS into a 2ohm load crossed over at 100hz.

Simple, conservative, clean.
( and fairly cheap )

I have 10ga power and ground wires on my HU. I have 4ga wires on my sub amp. I have 8ga wires running to my subwoofer. Everything is fused at the battery.

And to be honest, if I wanted to take my system to the next level, the next thing I would need to do is DYNAMAT the car.
I could buy more gear, but the next level for my system is "sound deadening".

I have no plans to do that.

Someone said that it "goes on and on and on..."

Not for me. There is a stopping point.
I have no problem working on systems for other people, but my system is finished. If I want better sound, I will come inside my house and listen to music on my home system. I have always been more into home systems than car systems. But we all like decent tunes in our rides, so we gotsta do what we gotsta do!