Hello guys.

  It's too complicated to get HD speakers for my SENA 10c EVO where I live, so I have already swapped the original speakers with much better ones, which I got from a broken headset Philips RB-HF520BE-K, nearly the same size. Pity, SENA does not provide speaker specs, but Philips does: Frequency range: 7 - 40 000 Hz, 40 mm, 16 Ohm and the sound is already much better. My question is, if there is a trigger for the HD speakers (like a resistor somewhere in the 10 pin micro USB connector) and if the HD option in the Sena app for Windows automagically understands that HD speakers (HD accessory) are connected and HD options become available. I reverse engineered the pinouts and connections, but still, don`t know someone owning the HD set so I can diff/measure it. Such post might be not tolerated here, but I have my reasons and SENA were contacted long ago about the issue.

Kind regards. 

* PS:

  Specs are much appreciated. "It's SENA compatible and HD" is not a description of a product..." All companies are fighting over specs plus/minus Hz/dB and we are here like "If it`s more expensive, it's better", "If it's for motorbikes, it has to be *3.14"...  Naaaah...