i have had these for a few weeks
my impressions is that they are good for the money (ofcourse)
they are great for games
they are okay for DVDs
they are mediocre for music...
i compared them to the Altec lansing ADA880 which i also own, compared the music playback with
just 2 speaker connected as the ADA880 does not have good back speakers
anyway, these speakers have an emphasized hi end, which makes music playback harsh on the ears (compared to if it was more balanced) also the 150-600k low end range is lacking resulting in a less meaty, realistic sound, playback borders on airy/lifeless.
the ADA880 interestingly enough is almost the opposite it has exagerated 150-600k and diminished hi end, so they are not perfect either, but this makes them softer which while it affects detail, does not make them harsh and fatigueing on the ears like the Z560s, so for that reason I really prefer the ADA880s for music and movies.
general advice when comparing speakers listening to the voices in movies, or the singing in songs is a great point of comparison, as there in no more familiar sound (to our brains) than the human voice, the more playback resembles a human voice the better the speakers, the less authentic the voice sounds the worse the speakers.
i have not compared the klipsch to the Z560s but I have compared teh Klipsch to the ADA880s, and going on memory alone i definitely thing the Z560s are at least as good as the Klipsch (if not better).
also 400watt speakers are all that much louder than 80-100watt speakers (maybe %20 at most)