I'm using this to send the audio output from a rear wall mounted projector to an amplifier and set of stereo front speakers. There is no perceptible audio lag. Works great, even in an area with heavy 2.4g WiFi crowding. My only complaint is the huge room-illuminating blue led on the front of each unit.
Sound quality is just awful: volume unstable, distortion, digital noise and huge isolation issues with supply. The different noises can sometimes be stronger than the music. The electronic engineers who've designed this should be ashamed, this belongs to the bin. Sometimes some sound equipment can have compatibility issues, so I tried with 3 different sources and 3 different earphones, no issue with my equipment.