I am noticing noise too. Using UE TF10's, just received them, and my newly received Ety HF3's too. Whether it is connected to a source or not, there is a small amount of infrequent noise; but It gets really bad when I connect it to my Samsung Nexus. I am looking for a well shielded portable amp for my phone now, as I would like to use my phone as my source to cut down on stuff to carry.
Currently I'm waiting for my L9 LOD to connect to my Gen 1 65Gb iPad, Gen 2 32Gb Touch and Gen 3 8Gb Nano. When connected to my nano with my DIY Canare/Swithcraft IC cable it sounds great. Waiting for my Monster USB cable for DAC use.
Right now I'm trying to find some really good quality music to see how it all comes together. A lot of my music is older and was not recorded with the greatest care.