Some news :
I mounted an Alpine MRV-T503 amp (2x50w rms).
It's better, the sound is more convincing, more in relief.
But this story of peak aggression has not changed.
While "playing" with the configuration of the tweeters, I realized that it is mainly the left tweeter that stings me. It is the one closest to the ear.
By unplugging the left, it's much better (but obviously the soundstage is destroyed).
In addition, I noticed that by sitting in the middle of the back seat, I did not have this worry of sybillances. Surely thanks to the fact that being in the back, we do not have the tweeters in full face.
All this leads me to conclude that it is not due to the tweeters themselves, but rather to their level.
Suddenly several solutions come to me :
_ Switch to another kit including a stronger attenuation of the tweeters (type -3db or -6db)
_ Switch to a bi-amplifiable kit, which would allow thanks to a 4-channel amplifier (2 channels for the woofers, 2 channels for the tweeters) to adjust the level of the tweeters as desired.
_ Keep my actually Hertz kit and switch to active filtering. But that doesn't really appeal to me.