The Kassandra uses the AD1865 chip, an 18bit R2R converter, which they say is probably the best sounding audio DAC …in fact they use 32 of them,16 converters per channel. 

The 16 converters in each channel work in complimentary mode, so that 8 converters are inverted. The two differential converter banks work in synchronicity  to achieve perfect symmetry. The 16 converters are working in current mode,and use an INtransformer so that the current differential is converted in single ended voltage output. No resistors or OPAMPS are used in the INconversion stage.

The analogue stage is implemented by a single ended transformer coupled triode stage, using the E280F,working in triode  mode, loaded with a  step down output transformer. The tube’s grid is driven by the secondary of the INtransformer  via an adjustable bias supply. The tube  power  supply is an oversized choke regulated supply. The step-down transformer  reduces the output  impedance  to 40ohms, with a maximum swing at full scale of 30Vpp sine wave.

The converter is equipped with an internal super-clock, which re-clocks the converters, making the processor virtually immune to transport changes, says the company’s press release. With the internal clock, there is no need for a word clock input. The super-clock re-clocker can be bypassed on the fly, so you can hear the effect of jitter elimination in your system.

The Kassandra Mk2 is available is signature version, with  upgraded power supplies. The Signature’s power supply is a complex system of a total of 8 toroidal transformers, for full separation of digital section, analogue supplies, clock supply and the tube circuits.