You can try reducing the number of sides in the arc. Or you might try using the Dave Method. That will require converting the speaker group to a component.
Does this look like what you have in mind? I only made it 1 mm.
For such a tiny feature, I just offset the border edges inward on the front by 1mm. I did another offset .5mm in from that one. Then I moved the outer perimeter edges back 1mm using Move with Autofold. Softened the outer perimeter edges and the 1mm offset. The inner offset edges were hidden.
The inner offset edges limit the softening. I unsoftened the outer edges of the larger round hole and hid them instead. Compare the difference in the front surface of mine with yours. Notice there are no weird shaded triangles on mine. That comes from those being not softened.