If you're going to switch to 15kHz, why did you even bother buying the XRGB2 unit? 15kHz is what the Neo outputs already. If you want to enable scanlines in 31kHz mode, enter the menu and choose the last option. If you REALLY want to force it into 15kHz (making it into an expensive useless lump of plastic) hold the DOWN arrow while you turn the unit on.
Lawrence.