I am about to order a gk 410rbh cab. I have a choice of a 4ohm or 8 ohm version. Should I go w/ 8ohm so that I can add a 1x15 later? Or should I get 4 ohm? In other words is the 1x15 worth it I.e. adding to sound or will I sacrifice potential volume by not getting the 4 ohm? As of now I think the 1x15 is a bit much. opinions?