Aurender AP 20 - Streaming Amplifier

AP20 – Reference All-in-One Music Server & Integrated Amplifier

The AP20 combines digital signal processing, D/A conversion, and power amplification in a meticulously designed unit. Instead of modular components, it creates a closed system where signal paths are short, interfaces are controlled, and interference is minimized. The result is not a "jack-of-all-trades" in the usual sense, but an integrated solution with a clear audiophile focus.

System architecture: Reduction without compromise

At its core is a complete dual-mono topology: separate signal processing for the left and right channels, consistently implemented from the DAC to the power amplifier. The AP20 combines:

• Streaming server with proprietary software platform
• Reference DAC based on dual-mono technology
• Analog preamplifier with relay-controlled resistor ladder (R2R)
• High-performance Class-D power amplifiers
• Linear power supply with multiple separate supply branches

This architecture not only reduces the number of devices required, but also avoids typical sources of error in complex chains: timing inaccuracies, ground loops, or inconsistent signal processing.

Power amplification: Purifi Eigentakt in dual-mono

The power amplifier section is based on Purifi Eigentakt 1ET400A modules, developed in part by Bruno Putzeys. In practice, this means very low distortion across the entire power range, high load stability, and controlled transient response.

With 200 watts at 8 ohms and 350 watts at 4 ohms, there is ample power reserve available, even for demanding loudspeakers. Crucially, it's not so much the sheer power output as the ability to reproduce dynamics without compression or harshness.

Linear power supply: Control instead of efficiency optimization

While many Class-D concepts rely on switching power supplies, the AP20 takes a different approach: six separate, toroidal linear power supplies specifically power the CPU, DAC sections, FPGA and power stages.

The goal is not maximum efficiency, but rather a supply environment that is as free from interference as possible. Especially when used with high-resolution digital sources, this has a direct impact on microdynamics and tonal stability.

D/A conversion and clocking

The conversion is handled by a dual-mono setup based on the AKM4497. High-resolution PCM and DSD formats up to DSD512 are supported, including full MQA decoding.

An OCXO-based clock generator with FPGA control reduces jitter to a practically negligible level. A 10 MHz master clock input is also available for external references.

Analog volume control

A key detail is the volume control: no digital scaling, but a relay-based R2R step attenuator in the analog domain.

This avoids resolution loss at low levels and preserves the structural integrity of the signal – a point that is often neglected in integrated systems.

Connectivity and Integration

The AP20 is designed so that both digital and analog sources can be integrated directly:

• Analog inputs (XLR, RCA) with true pass-through without A/D conversion
• Digital interfaces (SPDIF, BNC, TOSLINK) for external sources
• Network streaming via dedicated software platform
• XLR output for subwoofer or external amplification
• Headphone output for direct operation

The internal streaming and library management is based on a software environment developed over years, thus eliminating the need for external solutions.

Sound image

The combination of precise clocking, analog volume control and stable power amplification results in a presentation characterized by clear contours and stable spatial imaging.

Subtle dynamic details are preserved even at low levels, while large dynamic shifts are reproduced without audible compression. The AP20 delivers a controlled, non-analytical performance and maintains structure even with complex material.

Technical data

Generally

• Device type: All-in-one music server / integrated amplifier
• Housing: CNC-machined aluminum
• Display: 8.8? IPS LCD (1920×480)
• Dimensions: 430 × 360 × 150 mm
• Weight: 26 kg

Power & Amplifier

• Output power: 200 W / 8 Ω, 350 W / 4 Ω
• Amplifier modules: 2× Purifi 1ET400A (Dual-Mono)
• THD: 0.003% (1W – 200W)
• Damping factor: 800
• Output impedance: < 65 µO

power supply

• Completely linear
• 2× 400 VA (power amplifiers)
• 2× 50 W (audio sections)
• 1× 50 W (CPU), 1× 25 W (FPGA)
• Total capacity: 80,000 µF

Digital & Streaming

• CPU: Intel Quad-Core
• RAM: 8 GB
• System drive: 480 GB NVMe SSD
• Memory: 2 x 2.5" slots (user-installable)
• Software: Aurender Conductor
• Network: Gigabit Ethernet (double isolated)

DAC & Audio

• DAC: AKM4497 (Dual-Mono)
• Formats: PCM up to 32 bit / 768 kHz, DSD up to DSD512
• MQA: Full Decoder
• Clock: OCXO with FPGA control

Entrances & Exits

• Analog In: 1× XLR, 2× RCA
• Digital In: 1× Coax RCA, 1× Coax BNC, 2× TOSLINK
• Analog Out: XLR
• Headphones: 6.3 mm jack
• Master Clock Input: 10 MHz

Operation

• Power consumption: 47 W (operating), 80 W (peak), 6 W (standby)
• UPS: Integrated supercapacitors

The AP20 is aimed at listeners who are looking for a minimalist, technically clean solution – without sacrificing control, performance or sonic substance.