There exists certain delay between the SRC and the SNK due to radio signal processing, data buffering, and encode/decode of the stream data. Countering the effects of such delays depends on implementation. 也就是 A2DP 需一個 buffer 累積一些資料, 再一起壓, 如此壓起來的資料才會比較小, 但是就是會有一些 delay, headset profile 需要的是即時性, 並不能用這種方式.