The scandoubler is needed if your LCD cannot take the 15.5Khz sync.
The sync inversion will be taken care of by the scandoubler. Otherwise I beleive some silver dongle that converts Amiga to Vga form factor connector is to be used. I can't recall the exact name of the thing.
also if you hace a PAL system your LCD must be able to cope with the 50Hz refresh. Most LCD's require 56Hz and will not display a scandoubled amiga signal.
