Has anyone compared the E11 and the RSA Shadow if so what are the views. Is there a great difference in quality

I am a newbie to all this but am getting increasingly addicted to portable hifi. I currently have Westone UM2's driven through a Fiio E11. Whilst I like the SQ to a degree I am looking to upgrade. Music comes either from my iPhone 4 or Ipod classic 160gb. Mainly I use the set up whilst walking...