Who told you F&D F6000 is "a piece of crap"..?? F6000 is better than Z506 in many ways.... if you are having low budget then its ok.... but for budget dont compromise with quality....
F&D and Sony are crap,utter crap. Feed it some tough bassline they will curl up and die. Even tracks from Beat Dominator kills them, they are that crap, forget about soundstaging a Jazz Quartet with a Cello.
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It does better than them mate,anyday. It has much better panning across the channels and bass is pretty controlled at that price range. It dosnt over try and do something it cant like the Sony does or that F&D does.