Hi I've recently got a replacement from ebuyer, and the speakers are working great with the soundcard as its source, however I am having difficulties with the speaker picking up signals from other sources like ipod, psp, or the tv's headphone jack, even the laptop's headphone jack too. The sound coming out from these sources sound very un-natural as i can only hear some parts of the frequency spectrum and there is a hum in the subwoofer. Other than that the speakers are fine, I have also tried connecting it to the dvd player's phono sockets and it's working great but I'm just dazzled why wouldn't it work with other aforementioned sources. Is it natural or should I get another replacement? How about other z-5500 users out there? Do you have the same issues? Thanks