Lucky,
I don't have a PA800...(built in speakers) I have the PA2XPRO and the sound is AWESOME...but. you need to turn on the general master EQ and maybe tweek it for your sound system and room. (This is true for PA800 and PA2XPRO)

I use Mackie HR824 powered monitors..
When I demoed it in the store OOTB..I didn't love the sound either. I tries it with phones and I think Rolands small cube speakers...BUT when I got that baby home and did a little tweeking and hooked it up to my system...I was very happy.

Lee S.