Feature Request: independent line level output for audio jack

[alidaf]

This relates specifically to my experience with the SqueezeAMP v3.2 board but could be applied more broadly to other implementations and configurations although I believe it is dependent on the DAC rather than the ESP32 itself, so may not be feasible.

Currently, the audio jack can be configured to mute on insert or set to subwoofer (2.1 system) mode only. Subwoofer mode adjusts the volume along with the other outputs so it is more of a pre-amp out than a line level out.

I would like to see another option (if possible) to set the audio jack to a fixed line level out, i.e. unaffected by changing the volume of the spdif or amp output, even when the audio output is fixed to 100% in LMS, i.e. it should be at proper consumer line level (0dBV), not 100% of the pre-amplifier level.

This would allow the use of a third party pre-amplifiers/integrated amplifiers, or other peripherals that require line level input such as spectrum analysers, VU meters, recording devices, etc.

[sle118]

Interesting suggestion, but the feature would heavily depend on the chosen DAC, which means that the web UI or the LMS plugin would need to know if the hardware supports that to display or hide the option.

I'll let @philippe44 think about that and respond.