Crackling when played though the TV

Hey,

Love Rocksmith. I've been playing for years but never really learnt lead, this is exactly what I need.

I've got it setup on PC great. If I use my headphones it works great.

However, I also have my TV connected to my PC by HDMI cable. If I switch sound and video to the TV then I get crackling. It's not the cable (I don't think) because there is crackling during the intro ubisoft sequence.

I'd appreciate any suggestions.