My amp just connects to my sub
And the other side has the settings (bass, crossover, input level etc)
I am not into spending a ton of money on car audio, I hardly have it high enough to hear over the music. It's basically just filler so my speakers don't have to put out any bass but it gives the drums and bass more oomph
I think my amp was like $55, it's only 300w. It does what I want and I hardly have the bass up at all. It can rattle my car apart but I have no use for it.