stero pre amp- what does it do

[godzilla1]

Sorry to ask, i've googled but still cant work it out.

My rotel amp should be arriving soon. Rotel seem to sell a stereo pre amplifier. What does it do? How much of an increase in musical quality is there to be had? At £299 is it worth it?

thanks.

edit: apologies for the spelling error in title.

 

[huwg]

In simple terms it allows you to adjust the volume & balance and select the source input (CD, Tape etc). The output from it gets fed to a power-amp which amplifies the signal to drive the speakers.

An integrated amplifier (the most popular type) consists of both pre and power sections, but they are 'integrated' into one box.
The separate pre-amplifier will require a power-amp to partner it.

There are likely to be more detailed explanations to come, but in a nutshell that it what it does.