Two of them should be enough, the speakers are active, with built-in amplifier. 2 x 80 watts.

PreSonus Eris E5 (Active, 1 x 80 W, 1 pc.)

At the moment I would not like to spend more than CHF 250... For this reason, I am also very open and would look at various options in different price ranges.

What’s you Budget anne ( a rough estimate is enough) for the speakers??
Are you looking for a Bar or separate speakers that could be placed in individual rooms.