Hello everyone, I just wanted to let everyone know that I found the reason for noise in my system. Firstly, i took my first unit back as I thought that possibly it could have been one of the defective units. Slim chance I know. 2nd unit i bought home set up and yep same problem. After lollipoping about for a couple of hours I was ready to give up and i started to unplug it all ready to take back for refund. very disappointed. The first plug i went to pull out was the USB cable which was the only one that I hadn't tried. Unplugged it and BAM noise gone.
I post this knowing full well I could be the object of ridicule (fair enough) but some may not have tried it simply leaving it plugged in because this is how they edit their sounds.
Cheers and have a great festivus.