Help with Powered speaker setup- Hissing

I have the HS80M Yamaha Studio monitors which I have attached directly to an Oppo DVD player,which I use for both watching movies,and listening to dvd's.
I am using a cable that has one male end,which goes into the dvd,then splits into two female RCA ends,which are secured into the powered monitors. I have background noise,and hissing,even when the TV is off. Can I find a remedy for this irritating problem,by using different connectors?
The HS80m's incidentally sound UNBELIEVABLE for movies,being powered and with 8" woofers,aside from this problem.
Thanks
tracer