I purchased airport express and wanted to know what is the best setup to get the best sound quality over wifi. I have Edifier s530d speakers which have optical input.
If you want sound over WiFi it doesn't matter what kind of input your speakers have. For the best quality sound for a given pair of speakers, encode the files in a lossless format.
Optical cables all the way!
I have experimented with optical and very good quality analog to see how much of a difference there was and it was pretty clear