If one wishes to add in a sub, would one then need a 5 channel amp ?
Nope, I added a 10" powered Bazooka. Sounds amazing. Clean, can be adjusted so you can have it hit you with added bass or just a touch of bass. I have mine set at 25% and it has plenty of bass.
2012 Lava Red Mustang Coupe V6 with stone interior
Auto,2.73,BAMA Tunes 93H,Axle Exchange Aluminum DS,Pypes M80 mufflers,Airaid CAI,
Shelby GT500 racing stripes, Side window louvers,Side scoops,Polk Audio MM571 speakers
Shelby GT500 Steering wheel, Maxxim Maze wheels (18 lbs), BBK Throttle Body, Stillen Chin Spoiler, 10" Amplified Bazooka Subwoofer, Illuminated Door Sills, GT500 rear diffuser, Roush Rocker Panel Splitters, Splash Guards, Continental Extreme DWS tires