Metrum Acoustics ONYX DAC3 [2nd hand]

The designers at Metrum Acoustics developed the new Onyx DAC with the goal of creating a product that combines affordability with outstanding sonic performance.

It was an unprecedented challenge, centered around a completely new conversion chip, the DAC3, developed exclusively by Metrum Acoustics and first introduced in the Pavane model.

The R2R ladder networks employed in each of the four DAC modules—two per channel—together with the FPGA Correction Module, deliver superior performance. The FPGA module splits the incoming audio samples into two separate data streams, one for each channel. Each of the two DAC modules assigned to a single channel processes a portion of the data within the most linear operating range of the DAC chip. This approach results in extremely high linearity, reaching up to -145 dB, allowing the Onyx to achieve a true 24-bit effective resolution.

Thanks to its dual-mono architecture, channel separation reaches an impressive 120 dB across the entire frequency range. This ensures excellent soundstage reconstruction and precise placement of instruments within the virtual acoustic space.

In summary, the Onyx incorporates all the experience and expertise accumulated by the designers of Metrum Acoustics over the years, combining them into a high-end DAC that feels at home in virtually any audio system. The Onyx offers remarkable naturalness, employs NOS (Non-OverSampling) technology, and at the same time embodies all the technological advancements developed in recent years.

The sonic performance of the Onyx is particularly engaging because even the finest details contained in a recording remain clearly audible without ever becoming fatiguing. In terms of sound quality, the Onyx belongs among the finest playback systems available today, representing a synthesis of all the strengths found in Metrum Acoustics' flagship models, the Pavane and the Adagio.

A note regarding discrete R2R ladder DACs and why they cannot achieve the same performance as Metrum DAC3 modules:

1. Their component accuracy is typically limited to 0.01%, which means their effective resolution cannot exceed approximately 14 bits by design.

2. Temperature variations across the circuit board can introduce linearity errors.

3. They are highly sensitive to interference and humidity.

For these reasons, Metrum uses only laser-trimmed ladder networks to achieve perfect linearity and a dynamic range of 145 dB. Furthermore, the components are carefully encapsulated to prevent temperature-related drift and electromagnetic interference.

Technical Specifications

• Operating principle: Non-OverSampling (NOS) DAC. Forward Correction Technology. Transient DAC 3 modules – 2 per channel
• Power supply: 15 VA toroidal transformer
• Mains voltage: 220/230V AC, 50/60Hz
• Inputs: 1× Optical, 1× Coaxial, 1× AES/EBU, 1× USB or 1× I²S
• Outputs: 1 pair of single-ended stereo RCA outputs (2V RMS); 1 pair of balanced XLR outputs
• Frequency response:

• 1 Hz – 20 kHz (-1 dB) at 44.1 kHz sampling rate

• 1 Hz – 65 kHz (-1 dB) at 192 kHz sampling rate
  • Distortion: 0.006% THD
  • Noise floor: -145 dB at 2V RMS
  • Output impedance:

• RCA: 100 Ohms

• XLR: 100 Ohms
  • Supported sampling rates:

• Optical: 44.1 – 96 kHz

• Coaxial and AES/EBU: 44.1 – 192 kHz

• USB: 44.1 – 384 kHz
  • Output voltage:

• RCA: Max. 2V RMS

• XLR: Max. 4V RMS
  • Dimensions: 290 × 250 × 60 mm
  • Weight: 3.1 kg