Hello, I'm having the same problem, it's a more or less static noise/hum from the hardware. I have two great inear-headphones. Triple.Fi 10 and Westone 4. It's especially audible on on my tripple.fi which are very sensitive. I get none of this interference from my Samsung Galaxy Tab 10.1 or my iPhone 4.
I bought my TF700T in Sweden and have installed the latest update V.188.8.131.52
The thing is, if I pause my movie or music the noise goes away after a little while, It's quite obvious the system is shutting off the output when there is noting playing. I even tried this without headphones connected, putting my ear next to the speaker on the back, pausing my music/movie and I can clearly hear noise then after awhile it goes silent, the same as with the headphones.
Is there anyone else with this problem?
Is this common for Android and or ASUS/Transformer devices? Is there anything that can be done or should I return it and by another tablet instead?