Apostle,

I guess I should read before I answer. If you want to use that 600w for cuttings and it's too much light, maybe try indirect light. Never tried it, but if you had the light on or near the floor pointing up towards a flat white panel that is above your tray of cuttings, the reflected light would be way less intense. The heat would also be directed away from the plants. Adding a fan to blow the hot air away would help too. I don't know if it will work but you could experiment on cuttings that aren't weed so failures wouldn't be so costly. Good luck