CS2 center channel

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Anyone know resistance values for testing the speakers ? Also, parts availability on these ?
I was playing spirited the other night when the stereo display said ch sp wire then shut down. Upon restarting it sounded fine but the next day I noticed it was muffled. I tracked to and omitted for now the center channel. It works but is muffled sounding. No direct distortion out of any of the 3 speakers. Any assistance will be much appreciated.
Onkyo TX-NR636
Main - polkaudio Monitor 60's
Center - polkaudio CSI A6
Sub - polkaudio PSW10
Sub2 - polkaudio PSW505
Surrounds - polkaudio Monitor 40 series II
Front Height - polkaudio Monitor 40's
Audio Outdoors
Pioneer VSX 406 - polkaudio Atrium 5
Shed
Sony junker str-dn2010 with Sony bookshelf floor models and polkaudio R150's
Shed 2
Nakamichi soundbar