You'll have to excuse this general and low-level question but i need to know some stuff about amplifiers so that i can decide if i need to get one.

A)First of all, Do you think it helps to have an amplifier to process all audio signals before delivering them to the speakers?I mean is the difference noticeable when it comes to amp or no amp?

B)What are the gains of having an amp?Louder volume,less noise distortion,greater base and treble?Are the above statements true?

C)So how does it work?I mean how can you get more bass,less noise and louder volume without distorting the source?

I wonder why software equalizers fail to provide results when supposedly amp handle this kind of work,why is it that they're superior to this?

D)Finally,pre-amp vs amp vs power-amp?Why so many stages of hardware?Are they all needed individually? I hear that a preamp shapes the sound and drives it to the poweramp that drives it to the speakers and a system combining the two together is an integrated amp.This is whai i get so far.

Again i apologize for these questions, but i need someone to take me back to the basics.