Hello everyone. I'm a complete newbie in this forum, so I hope to be treated with only moderate violence... ;-) Anyway, here is my problem: I'm a proud owner of a Yamaha RX-V420 receiver, connected to Toshiba DVD and Magnat 5.1 satellite speaker system. Everything worked great, until I've connected the receiver to Samsung digital CATV decoder. This connection created a really annoying humming noise (at a very low frequency), that constantly came out of my speakers. I SOLVED this problem by grounding the CATV cable, creating a "grounding tree" of two wires, grounding the two edges of the CATV coaxial cable to the same point. BUT, when I've tried to connect the SPDIF digital output of my new computer to the coaxial digital input of my receiver, the horrible noise has returned, and became even louder (even though I do hear AC3 sound through my SPDIF). Does anyone have any idea what is the reason of this noise and what practical steps can be done in order to prevent it? I thank all of you in advance, and hope you'll excuse the length of my sad story... 10x!!!