Hi thank you for your reply.
I'm using a standard HDMI cable connected into my graphics card which is an NVIDIA GeForce GT 640.
Looking in Device Manager under sound,video and game controllers it says NVIDIA High Definition Audio device as well as High Definition Audio Device.
My PC otherwise is old the Graphics Card I purchased 3 years ago.
Does this mean I shouldn't need to worry about changing anything and I'm already getting the best quality I can get for music when playing on my PC to the AV over HDMI?
Is there a recommendation as well for HDMI lead? I'm just using a standard £12 one.