ЦАПы — Aries Cerat Kassandra Reference

The Kassandra Reference is an R2R digital-to-analogue converter with a tube output stage from Aries Cerat, and today it is offered as the Kassandra II Reference at GBP 24,950 in the UK. It sits below the Kassandra II Signature and Limited Edition models in the Kassandra family, and the company notes that the original Kassandra began as an internal laboratory tool rather than a commercial product.

Key specs that matter

Conversion uses 16 AD1865N-K R2R chips per channel in two banks of eight, without oversampling or a digital filter. The output stage is built around an E280F tube connected as a triode and loaded by a transformer, with a step-down output transformer of 5 to 1 or 10 to 1 and a double choke-filtered power supply. Output impedance is 50 ohms on balanced and single-ended outputs at the 0 dB setting, with 10 V RMS output, or 12 ohms at the -6 dB setting with 5 V RMS. Inputs are USB up to 24 bit and 384 kHz, S/PDIF and Toslink, while the analogue signal leaves through two XLR pairs and two floating RCA pairs whose ground can be switched. The unit measures 540 x 520 x 165 mm and weighs 60 kg.

Engineering and use context

Each AD1865N-K is a multibit R2R converter chip, and combining 16 per channel shares the conversion across many chips. Running without oversampling means the original samples are converted directly, with no interpolation. The E280F is a pentode used here in triode connection, and the output transformer steps its voltage down, which lowers the output impedance and increases current capability. The two step-down ratios give the two output settings, trading maximum level for lower impedance. Double choke filtering smooths the high-voltage supply for the tube stage with two inductor sections. The floating RCA outputs, whose ground can be switched, help deal with ground loops in a system.

Pairing

With its high output level and moderate output impedance, the Kassandra Reference can drive a power amplifier directly if volume control is handled elsewhere, or feed any preamplifier. The lower-level setting suits amplifiers with high input sensitivity. Digital sources such as a USB streamer, a CD transport over S/PDIF or a TV over Toslink connect directly.

Alternatives

The Aries Cerat Ithaka is the larger R2R converter of the Ianus series, using 24 AD1865N-K chips per channel and a TriodeFet output stage with 1 ohm output impedance.