Just picked up two additional subs. I can't do the math to calculate the ohm load for this application. I've got four 4ohm subs that I'd like to push with my cheap old MTX 4250d. The four subs do match. I've looked over the wiring diagrams on the web, but I'm confused a bit by the internal wiring on the MTX amp that apparently drops the amp down to a 2 ohm load if wiring two 4ohm subs straight to the two channels. Would you advise wiring all four subs in series, split between the two channels, do some sort of parallel/series split, or what. Any advice would be appreciated. Boating season is closing in and I've got to get this straight so the boat will bump just a bit harder.