Spotify bit rate using apple tv

Hi,

I am a spotify premium user and mainly use it to stream via ipad2 > apple tv to my avr.

I am under the impression that I'm only receiving 192kbps due to it being a mobile device?

How do I up the bit rate while keeping the flexibility of wireless steaming?

I don't want to use the pc as its my wife's and she has her own iTunes, spotify etc. 

Matt