Integrated amplifiers — Gato Audio DIA-400S

The DIA-400S from Danish maker Gato Audio is a Class-D integrated amplifier that includes its own D/A converter, delivering 400 W per channel into 8 ohms and twice that into 4 ohms. Analogue XLR and RCA inputs sit beside USB, Toslink, coaxial and aptX Bluetooth reception, so one box can take a turntable preamp, a laptop, a TV set or a smartphone.

Key specs that matter

Frequency response is 20 Hz to 20 kHz within 0.5 dB and 2 Hz to 70 kHz within 3 dB. Below full output, distortion remains under 0.01%, while noise sits more than 110 dB below the signal. Input impedance is 20 kOhm on RCA and 40 kOhm on the balanced sockets, voltage gain is 26 dB with 10 dB of headroom, and the recommended speaker load runs from 4 to 16 ohms. The line outputs reach 13 V balanced or 6.5 V unbalanced at 75 ohms output impedance, with distortion at the pre out below 0.001%. The chassis measures 325 x 105 x 420 mm and weighs 13 kg.

Engineering and use context

The output stages combine switch mode power supplies, precision MOS-FET switching transistors and output filters built from polypropylene capacitors and low-resistance coils. An analogue input stage links the external inputs and the internal converter to the power section. The converter section is fed from a dedicated supply and drives a Burr-Brown PCM1794 chip in balanced mode, and the asynchronous USB circuit accepts signals up to 24 bit and 192 kHz. Apple tablets and phones running iOS 7 or later can stream over USB through a camera connection kit, and Bluetooth pairing is shown by a BT Connect button that blinks when ready and stays lit when linked. A Direct mode on input 1 bypasses the volume control so the unit works as a fixed level power amplifier within a surround system, and the setting survives standby and power-off. Protection warnings appear on the display as a blinking HOT sign for overheating or an OFF sign after a fault, a large white LED dot matrix display reads out the incoming sample rate, and an RC-3 infrared remote is supplied. Mains supply is 115 or 230 V at 50 or 60 Hz, with consumption below 1 W in standby, 35 W at idle and up to 1600 W at full output. Fusing is by an 8 AT sand-filled 20 mm type, and the manual asks for 100 mm of free space around the heat sinks.

Pairing

Banana terminals carry the speaker outputs, while balanced and single-ended line outputs plus a 12 V trigger allow an external power amplifier to be added later for bi-amping or extra channels.

Alternatives

Gato Audio also makes the DIA-250S integrated amplifier with converter, rated at 250 W into 8 ohms and 500 W into 4 ohms with a weight of 10 kg.