Actually, by powered, do you mean powered seperately or BY the PB.
If you just mean mains powered speakers, I use the Videologic Sirocco Spirits, which should cost about US$150 now. Two boring black boxes, I admit, but they sound good, have inputs for headphone outs from e.g. iPods, portable CD, and a line in. Also, it has an output for a seperate subwoofer, but the bass isn't too bad anyhow.
David