If you have 2 4 ohm subs you can wire them to show a single 2 ohm load or two separate 4 ohm loads. If you have 2 DVC 4 ohm subs you can wire them to show a single 1 ohm load, two separate 2 ohm loads, or two separate 4 ohm loads (only use one VC connector) and possible one 2 ohm load. Someone correct me if I'm wrong. It all depends on what your amp is stable too. The DVC subs give you greater flexiblity if you plan on upgrading to a different amp, but usually cost more.