Left speaker makes sizzling noise. This started suddenly when the HT system was turned on. I turned off the HT system, but the noise would not go away. I disconnected the speaker, unplugged the powered cord and replugged it, the panel started sizzling again. Waited about 30 minutes, replugged it, here comes the noise again. The level of noise is high and quite unpleasant. Is this the end of its lifespan? Thanks for any input.