the LED is designed for an 80x80 so it should be sufficient what surprises me is the 150w, great savings I have a 270w lamp and the box is 2 meters high, if I leave the lamp too close I have problems with the apical buds, the power (I should reduce it a bit) creates plants with small apicals and the remaining flowers are much larger so if you add a lamp you need to reduce the power of both, increase fertilization, air circulation, and watering times and if you have the possibility, increase the CO2.... that's why I was saying to enhance the ventilation the increase in yield is still proportional to the box, normally I do 4 plants and more than about 100g per plant I can't do due to limited space

Yes. It can.

You don't need 2 in an 80x80. And no. Its not like where you c in the factory where they double the size the ppfd goes up. They are designed that way. The light/heat stress alone is not worth it. Though if you have some shading.. you can push 1 right to 1c side and vice versa and slowly start of with 80% at 40cm and then move down. But, in reality if I were you. Get another 80cm2. Then you'll have double the storage for plants. Good luck.

yes it can. but watch to not burn them :)