Sound muffled on HW-R450

[Michael Stanton]

I bought this sound bar for my father and has worked great until just recently. When we turn his sound bar on it immediately gives a very muffled sound and cannot hear what is actually supposed to be heard. Any idea why this is happening?

[TechSupportUK]

is this connected via an optical cable or Bluetooth? (also...silly comment but just check the cable is in properly)