Yeah you are very right I learned...They do make some high frequency single ended bulbs, but I didn't realize you can't use any single ended. I just came across these 1100 watt high frequency bulbs that look awesome, and a killer sale....but shit, this complicates things even more in my ballast search !The DE ballasts typically drive the lamp at 400 volts so I dunno how long the single ended lamps will last.