did you take the cover off and put your ear by the tweeter ?
maybe it came disconnected ?

and I am sure you told your reciever you have a center channel now ?

I have a vp100 and it sounds anything but muffled, so you definitely have something going on there.

even less likely a problem is a polarity problem on the hookup wires, but I imagine your receiver woulda caught that during the autosetup

good luck

Randy

Axiom M80, Ep600, Qs8, VP150, Crown XLI 2500 , DBX Driverack PA2, Focusrite Scarlet 2i4