had to get new surrond system but could'nt afford true dolby hd. so i got a panasonic sc-pt480 which is connected to my sony bdp-s370, via an optical cable. at first i could'nt get the sound to play during movies so i changed the things to pcm? but when i play a movie now the front speaker dos'nt work? i get the talking from the front speakers? also when theres a quiet bit in the movie i can hear a loud hum from the panasonic unit?