i dont have the 540's ive got a set of 530's(i've had for 4 years and still work great), which are basically the same thing just don't have the center speaker tooth. (allows mounting center speaker ontop of lcd monitor)
as far as 5.1 goes they are nice, if they are only just a tweak on mids, they shouldn't be much different; the rear speakers could probably use a little more power over the front set, the center is loud enough, as 5.1 they work well enough, you just might feel a need to tweak the power here and there depending on the game/movie on individual speaker output. but that may be a bit different from me b/c i've got pretty low hearing in my right ear, but whatever...
basically if you want to pump them they will pump or they can be low toned for when people don't want to hear it.
thats all i have to say.
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