The AH20 is a fully balanced DACl & preamplifier / headphone amplifier with relay volume control circuit (hardware). Equipped with the best conversion technologies, it uses two excellent AK4497EQ chips in conjunction with a high-performance XMOS USB interface and has an I2S input on an HDMI connector.

This DAC / headphone amplifier will delight audiophiles looking for a very high level compact system for transparent and clear decoding of high definition digital files. It will ideally match HiFi systems of any degree of complexity and offers interesting integration possibilities, notably thanks to its balanced and single-eded outputs which are activated simultaneously.

Full symmetrical DAC AKM AK4497EQ

The digital to analog conversion stage uses a 32-bit AKM AK4497EQ chip combo.
It takes advantage of the famous Velvet Sound architecture of the brand, making it possible to develop sound details of incredible richness while largely limiting the distortion of the signal.

Each channel of the stereophonic signal uses its own DAC chip. This makes it possible to develop an astonishing richness in the resolution of the signal, each of the two chips dedicating 100% of its computing power to a specific channel. This full symmetrical integration feature offers an incomparable level of crosstalk with impressive precision in channel separation. This plays a considerable role in the construction of a detailed sound scene with a clear stereophonic image & spatialization.

The Velvet Sound technology developed by AKM benefits the sound rendering and develops immersive dynamics and integrates 6 selectable reconstruction filters to adapt the behavior of the DAC to the specifics of your audio system and your listening preferences.

The digital signal is processed by CPLD (FGPA Altera) to fulfill the functions of logic, clock management, PLL, DOP demodulation and PCM / DSD antipop.

XMOS U8 USB interface with Accusilicon clocks

The Gustard A20H has a very high quality XMOS U8 USB interface with 8-core controller completely up to date with the latest USB Audio standards.

The latter supports DSD64-256 & PCM384 kHz digital streams and is supported in most current operating systems: Windows XP, Vista, W7, W8, W8.1, W10, MacOS, Linux Kernel and can even partially work with Android and OSX devices if they have an OTG function.

Gustard A20H's integrated USB interface uses two very low phase noise and extremely precise Accusilicon clocks. The model used is one of the best clock references available for digital audio and considerably limits the need to correct errors in digital cycles that can cause unwanted noise and distortion.

Clean dual power supply

The A20H benefits from an extremely efficient power stage based on two regulated linear power supplies with 2x isolated 50W toroidal transformers. This makes it possible to supply the digital and analog stages very cleanly while carefully avoiding the pickup of noise from one circuit to another.

The supply stage is then divided into several sub-units of powerr with individual filtering and voltage regulation for each interdependent block of the circuit. This ensures excellent power stability while limiting local stresses on the components.

Discrete balanced headphone amplifier

The Gustard A20H has a fully discrete and balanced amplification circuit operating in pure class A.

Its balanced and single-ended outputs are active simultaneously.

The headphone amplifier stage is capable of providing comfortable power up to 2400mW at 32Ω and 132mW at 600Ω. Or a reserve of sufficient power to power difficult helmets.

Measurements

Distorsion

Frequency response

SNR

THD+N