The multi-channel power amplifier shall use digital class-D circuit topology and shall be configurable to allow two, three or four channel operation. Power output in four-channel mode with all channels driven shall be: 500 W at 100 V (20 ohms). Total harmonic distortion (THD) shall be less than 0.1% @ 1 kHz, 0.3 % (100 to 20,000 Hz). The frequency response shall be 50 to 20,000 Hz (4 dB). The crosstalk shall be 70 dB (A-weighted). The input impedance shall be 10k ohms for each input into an electronically balanced input circuit. Rear panel switches shall allow selection of bridged operation for each pair of channel (1-2 and 3-4) independent of the status of the other pair of channels. A rear channel input mode switch shall allow the selection of input 1 to all mode, whereby the signal from input 1 is simultaneously fed to all other channels. Each input shall feature a 3 pin phoenix block and XLR connector. Rear panel output connector shall be a heavy gauge M4 screw-terminal barrier strip suitable for use with spade lugs or up to #12 AWG bare wires.The front panel attenuators shall be recessed to prevent accidental level changes and may be removed and replaced by included security covers once levels have been properly set. The front panel shall have four sets of four LED indicators to indicate the following conditions: signal presence at input (greater than -20 dB), signal presence at output (greater than 1 W @ 20 ohms load), peak clipping, and protection circuit activation. The front panel shall also have four removable air filters that may be removed for cleaning without removing the amplifier from the rack. The amplifier shall be forced-air fan cooled with the air intake at the front and exhaust at the rear.

Built-in protection circuitry shall monitor voltage and current levels to minimize potential damage from overloads and disable output during shorts, DC offset or excessive operating temperature at power amp heat sink over 100°C or excessive operating temperature at power supply heat sink over 80°C via a relay for each channel. The relay shall also delay amplifier connection to the load during turn-on for about 2 seconds, so as to prevent any occurrence of noise at turn-on. Power consumption shall be 460W (based on EN standards) and 2350W (rated output 8ohm x 4 channels). Each channel shall be equipped with control/monitor terminals to permit power on/off control of each channel, status monitoring of power on/off and protection for each channel and fan operation. The control panel and monitor display shall be a custom made non-TOA piece. The control/monitor connection shall be made via two RJ-45 connectors. The amplifier shall use two standard rack-spaces or 88.4 mm and its dimensions shall be 482 (W) x 88.4 (H) x 404.2 (D) mm. Front panel finish shall be black anodized aluminum and case finish shall be sheet steel. Weight shall be 9 kg.

The amplifier shall be a TOA model DA-500FH.