Review The Class Audio DELTA Pre Amplifier and Stereo Amplifier Review Audio Outputs Banana Speaker Jacks. Distortion THD+N at 1kHz into 8 ohms. In full and glorious working order, delivering a potent 175W of Class AB bliss. This item can be shipped to United Kingdom. Input Impedance 440kohms, 470pF Unbalanced Input / 200kohms for Balanced XLR input.