AirPlay has always been reliable for me as long as the network is reliable. Using 802.11b Wi-Fi to stream music from an old, underpowered computer can be a problem. That being said, I've gotten audible benefit to re-clocking AirPlay S/PDIF data signals with some DACs.
@zm I think the Pro-Ject Stream Box S2 Ultra does do what you're looking for, but I haven't tried it myself so I'm just going by the documentation. Pro-Ject's products have always been good quality in my experience.