[fidelramos]

From the article:

> Each A2DP service, of possibly many, is designed to uni-directionally transfer an audio stream in up to 2 channel stereo, either to or from the Bluetooth host.

This matches what I has heard: Bluetooth devices with A2DP profile can either receive or send high-quality audio, but not both at the same time.

I don't know if there are Bluetooth headsets that have separate A2DP devices for input and output sound, I have never heard about them, but I would be very interested in knowing of their existence.

Also from the article:

> These systems often also implement Headset (HSP) or Hands-Free (HFP) profiles for telephone calls, which may be used separately.

This is the common case for Bluetooth headsets, the Bluetooth manager switches profile when the microphone is needed, but that greatly reduces audio quality.