AUDIO-GD HE-27 DAC Preamplifier Headphone Amplifier Black

The Audio-GD HE-27 is a high-end DAC / preamplifier and headphone amplifier featuring a fully discrete and balanced architecture along with proprietary ACSS technology without feedback. It incorporates four PCM1704UK R-2R conversion chips, renowned for their natural sound reproduction, combined with an Amanero 384 asynchronous USB interface with FPGA-synchronized clocking, supporting PCM streams up to 32bit / 384kHz. Two ultra-high precision Accusilicon TCXO oscillators operating at 90MHz and 98MHz synchronize all sampling rates without relying on PLL oversampling. All digital circuits and digital inputs are fully isolated from the analog stages to minimize interference. The HE-27 also features an IN2 coaxial input that can be reconfigured via firmware update into a 10MHz / 75Ω external clock input.

Its fully balanced preamplifier and headphone amplifier section operates in pure Class A and is based on four no-feedback output stages composed of eight transistors, each capable of handling 15A / 150W. The internal power supply relies on four R-Core transformers delivering a total of 160W and a filtering capacitance of 50,000µF. The unit delivers up to 10W into 25Ω and 1000mW into 300Ω, allowing it to drive the majority of headphones available on the market. Volume control is achieved through relay-controlled I/V attenuation using 0.05% precision resistors, offering 100 adjustment steps and perfect channel matching across all four channels.

Audio-GD HE-27: Analog regenerative power supply

One of the HE-27's key features lies in its analog regenerative power supply, comparable to an integrated electrical generator. It recreates a pure 50Hz sine wave using dedicated analog circuits powered by Class A parallel regulators. This technology significantly reduces mains interference and improves transparency as well as channel separation.