Correction to previous posts: the other colour that lights up on my Fiio K5 PRO ESS isn't green, it's yellow, though it does have a greenish hue (that makes more sense I suppose). So, when I'm using Wiim mini as wifi transport, the light is blue for Amazon Music HD quality and yellow for Ultra HD. BUT when I connect the Fiio K5 PRO ESS to my Windows computer and use Amazon Windows app, the colour now is ALWAYS yellow. So yes, there's some DSP going on. I always check the exclusive mode toggle (you must have exclusive mode enabled from the settings menu, but also enable it for the music you are playing inside the devices menu every time you open the app). So this is what lots of people complain about on Amazon Forums: exclusive mode doesn't prevent Windows from meddling with the bit rate. Obviously, now it's resampling it to the rate that has been established on the audio advanced settings menu.