While I personally agree with these points, I'd just like to point out that the third one could be problematic in case auto-gain is forced instead of made configurable.
IMHO if EQ auto-gain option is ever introduced, it should absolutely be made optional (i.e. have an on/off switch) and also have the possibility to be overridden with user-defined manual pre-gain values (like you already suggested).
Here's a few examples where
forced auto-gain might be undesired:
- Backward (in)compatibility
- Current users of EQ might not want their existing system to start behaving differently (i.e. decrease in level) after a new feature (auto-gain) is introduced.
- If one wants to compare how two different EQ profiles sound.
- If the two profiles result in different auto-gain values the overall track loudness would change accordingly when changing the EQ profile - making the comparison meaningless. I.e. it only makes sense to listen to EQ profiles with identical pre-gain settings.
- As mentioned in my previous post, in cases where we don't regularly max-out output level, adding auto-gain would just decrease the overall output level without really bringing much benefit.