I guess it's AAC, as the display shows that it's got more Kbs than MP3? As our FM signal is very poor here, I've been forced into getting one of these reasonably priced devices to listen to Radio 3 on my hifi. Is this the highest quality stream I can get or are there other devices or methods I should try? Any comments, suggestions or advice much appreciated as I'm new to this whole area of streaming/internet radio or whatever it's called! 