Audison Prima. Audison AP 6.5 Prima Speakers 4 ohm. Audison AF M5.11 bit Forza Amplifier 5 Channel 4x150w + 600w 11-Ch DSP 1200w RMS. To extend the woofer's frequency range down to low frequencies up to 50 Hz a 75 Hz resonance frequency has been chosen, achieving excellent low frequency output even without the use of a subwoofer.