ALAC (that I use) is also compressed. Format makes difference only if your method of delivery affects timing of the DAC, for instance S/Pdif. When you use WiFi, Ethernet or async USB format doesn't matter since music is delivered as data. In fact nothing on the side of computer matters (computer speed, type of HD, amount of memory). Playback program also doesn't matter as long as it is bit-perfect (doesn't upsample etc.). Electrical noise from computer can always affect sound of your DAC. Because of that I selected WiFi, plugged computer into different outlet (on different phase) and use conditioner for my Airport Express, DAC and Power Amp. Airport Express jitter still matters, but my DAC suppresses it. If not for the distance form my computer I would go with Ethernet or async USB.