Keyboard going into PA: need Direct box/preamp?

[SKYflyer]

My band has a PA, and we plug my keyboard into it, by connecting them with a regular 1/4 inch cord. My keyboard doesnt sound great thru the PA, and we think it is because the PA is not of great quality. My bandmates think this can be improved by doing one of two things, or both.

They think it will improve the sound quality by making the keyboard go thru a direct box or a pre amp or both of the above devices before connecting it to the PA.

Now, as for the direct box, i am almost certain this is an absurd idea, because my understanding is that for short distances (my keyboard is 10 ft away from the PA), a direct box will do nothing. It would only help get rid of noise if my keyboard was a long distance away from the PA, and we are not suffering from any noise problems currently. Am I right about this or is my friend? (he thinks somehow the direct box will magically improve sound quality)

As for the pre amp, i am also skeptical as to its benefits, although not as much as i am concerning the preposterous direct box suggestion. I understand that the keyboard does not need a preamp going into the PA because it is already amplified enough (line level, i think is the proper term?), whereas something like a guitar would of course need a pre amp to sound good, a regular keyboard does not need a pre amp to improve its sound quality thru a PA. Who is right in this case, me or my friend?

Thanks for your help.

EDIT: actually, my band uses a powered mixer, not a PA head (just to clarify things.)

[AlChuck]

A direct box is for taking a instrument level signal (as from a guitar or basspickup) and bringing it to line level for insertion into a line input on a mixer.

The output of a keyboard should already be line level. So neither a direct box or a preamp (which is for mic level signals) is going to help you very much at all as far as making the sound coming out of the PA any better.