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: 250 W per channel into 40 ohms (100 volts). Total harmonic distortion (THD) shall be less than 0.1% at 1 kHz and less than 0.3% from 100 to 20,000 Hz. Frequency response shall be 50 to 20,000 Hz (-3 dB, +1 dB). Signal to noise ratio shall be 100 dB below rated output (A weighted). Crosstalk shall be better than 70 dB (A weighted). Input sensitivity shall be +4 or -10 dBv (jumper selectable) for rated output, where 0 dBv = 0.775 volts RMS. Input impedance shall be 10k ohms for each side of an electronically balanced input circuit. A rear-panel input mode switch shall allow the selection of  "channel 1 to all" mode, whereby the signal feeding the channel 1 input terminals is simultaneously fed to all other channels. Rear panel input connector shall be a 3-pin removable terminal block for each channel. Rear panel output connector shall be a heavy-gauge M4 screw-terminal barrier strip suitable for spade lugs or up to #12 AWG bare wire. 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 for each channel: signal presence at input (greater than -20 dBv), signal presence at output (greater than 1 W at 40 ohms), peak clipping, and protection circuit activation. The front panel shall also have removable air filters that may be cleaned and reinstalled without removing the amplifier from a 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, excessive operating temperature at power amp heat sink over 167°F (110°C) via a relay for each channel or excessive temperatures inside the unit over 176°F ( 80°C). The relay shall also delay amplifier connection to the load during turn-on for about 2 seconds, so as to prevent any concurrence of noise at turn-on. Power consumption shall be no more than 200 W when all channels are driven with continuous pink noise at 1/8 full power into 40 ohms (Based on EN standard), and no more than 1,150 W when all channels are driven with continuous pink noise at full rated power into 40 ohms.

The amplifier shall use only one standard rack-space or 44.5 mm(1.75") and its dimensions shall be 482(W) x 401.8(D) x 44(H) mm (18.98" x 15.82" x 1.73"). Front panel finish shall be black anodized aluminum and case finish shall be sheet steel. Weight shall be 6.8 kg (15.0 lbs.).

The amplifier shall be TOA model DA-250FH.

The optional 1:1 line isolation transformer shall be TOA model MT-251H