In theory, no. In reality, you will be limited by some of the DACs which are included within the componentry you are purchasing. That is, cheap gear combined with great audio = cheap audio. But, it is still cheap GOOD audio. So, it is nothing like an MP3 which would be cheap bad audio.
It is also possible for some of the data to potentially be lost, but that is highly unlikely with the reliability of most networks these days. So, I expect that what you will hear will be a fair shot better than MP3 and as far as I know there is not one extra bit of compression that takes for the Airport. It simply streams the lossless audio from point 'A' to point 'B'.