I'm looking for a driver that can handle 6 D cell batteries in a series configuration. 1.5v x 6 = 9v and I understand under a small load the input voltage will drop a bit (more like 1.3v x 6) but still what driver would be best for this application? I'm looking for a driver that can do this and is very efficient, and maybe even 4 modes. It will be driving an XM-L LED. I don't mind paying $20 or a little more for a quality product.