TV: 50" Panasonic Viera 720p plasma (TC-P50X1) BluRay player: Panasonic DMP-BD60 Surround sound system: Panasonic SC-HT720 5-DVD player and surround sound. (It's an older unit, with great sound, that I only use to pump the audio thru now. I play all DVDs and BluRay discs on the DMP-BD60 now.)
MY PROBLEM:
From the BluRay player, I go HDMI-out to HDMI-2 on the TV. (cable tv signal uses HDMI-1) But being my TV only has an OPTICAL AUDIO output, and the surround sound system only accepts ANALOG (RCA) type audio inputs, I have to use regular analog audio cables (white/red) from the 'AUDIO OUT' outputs on the back of the BluRay player and into the back of the surround sound system. This SHOULD send the audio output of the BluRay player to the surround sound system just fine.
I'm getting a slight low-pitch "humm" (especially heard thru the subwoofer) when I connect the analog audio cables into an audio input channel in the back of the surround setup. When I disconnect the HDMI cable from the back of the BluRay player, the humm goes away. Could it be because the HDMI out also carries an audio signal, and with the analog audio out cable are also carrying an audio signal? I don't think that should make ANY difference though. I've tried 3 different HDMI cables, they all cause the BluRay's analog audio output to humm. Same with trying different sets of RCA analog audio cables. I've tried plugging the RCA cables into different input channels on the back of the surround sound, makes no difference. As long as the HDMI cable is plugged into the HDMI-AVout on the back of the BluRay unit, and I'm using analog audio cables from the AUDIO OUT outputs on the back of the BluRay player into an input channel on the back of the surround setup, it causes a humm. Almost sounds like a bad ground-type sound, but I'm not sure how to test for that. The BluRay player is pretty new, and I've never had this problem with it before. This problem just started out of the blue. I have RCA cables going from the analog audio output of my cable box and into the surround sound unit, no problem at all. It's only with the analog audio output of the BluRay player.
What could be causing this? Any help/suggestions would be appreciated.