The Surge 8 is specially engineered to run and conquer your sub woofers with zero distortion and extreme power. This ampliefier originates from a CLASS TD circuit for higher efficiency and output voltage. The pure copper toroidal transformer produces unmatched power and helps your sub woofer to produce BASS BEYOND BASS. The inbuilt crossover helps you cut the unwanted frequencies to your sub woofer with no need of any external device. It is perfectly tuned for your dual 18″ or 21″ subwoofers with up to 5″ voice coils.