How do I decrease to 0 the audio of a spatial sound?

This is my actual config:

i.paste.pics/2d7b7c658648755e093a9f550b0ad286.png

i.paste.pics/ba488272fdabc97c8507e29dd1853450.png

At some point it not reduces the sound ¿?

I tried maximun distance, but not matter if i set 1 or 10000, the sound reduces constantly until x point and stops. So you can still hear the sound.

I can play with Roll-Off and Reference distance to make reduction to 0 but it reduces so fast, i want to reduce to 0 constantly from close to 1000 pixels for example.

Maybe the Maximun distance is bugged? Because it should stop reducing at X pixels and as said, no matter if you set 1 or 10000. ¿?