[jamesbrown838]

Hope someone can help. I am using pioneer bluray and it is connected to a yamaha 4600 receiver using hdmi. I use the yamaha preouts to connect to the p8 preamp ht bypass then to nuforce mch 2- 5 power amp. There is quite a loud noise hiss from my speakers. If I connect hdmi to tv and use a coaxial no problem. Same happens with oppo dvd player with hdmi. I have 5.1 rca outs on oppo and it hisses badly as well when connected to receiver and again not coaxial. Does the problem lie with the yamaha as it is only hdmi 1.0 but then I don't understand why rca 5.1 don't work to well  either.

[rustydoglim]

Your ground loop noise could be from any equipment. Email support and Casey might be able to give you a few suggestions. Basically you need to play with your setup to identify the ground loop noise. Try to use a cheater plug (ie to remove the ground) on the DVD player or source device to see if that will cut of the ground loop.

[jamesbrown838]

Thanks Jason I will do that now. I am not electrically minded so you will have to take it easy on me.

[ted_b]

Describing it has "hiss" doesn't make me think ground loop hum.  Ground loop hum is 60hz and is a very low audible bass hum.  Hiss is sometimes due to lack of input signal on the amp.  I have hiss in my system if processor is off and HT bypass is selected, but dead quiet wehn proceesor is on.  Try turning on the processor vs it being off  (or try plugging all sources into same electrical line, although that's usually hum-induced too, not hiss).

[jamesbrown838]

Thanks again sorry I would describe it as more of a loud hum than speaker hiss. I tried switching off yamaha and then switched on the HT Bypass and the loud hum was still there so any ideas. The only real change I have done is I use the balanced preout and rcas for bi amping and the balanced were used for the highs and rca for lows and I changed them round and I have to better music but would not have thought that would give a loud hum on the bypass. Also now when starting up the power amp the pops that come from speakers.,the first pop is a lot louder than it was before so I dont know if this is all part of it. I have checked all cables and they are OK