Alpine 432 Power Density Digital Amplifier - PDX-F4 Alpine PDX-F4 4-Channel 400W Amplifier TRUE RMS POWER: 100 watts x 4 at 4 Ohms | 100 watts x 4 at 2 Ohms | 200 watts x 2 bridged 4 Ohms 4 gauge power and ground, up to 8 gauge speaker Frequency Response: 5 Hz - 100 kHz / 0dB ~ -3dB (Reference: 1 W into 4 ohms)