Your correct it does use tube rectifiers in the dac
Cheers George
The BorderPatrol DAC uses a R2R DAC chip with no over-sampling and no digital filtering fed from a very sophisticated choke input, tube rectified power supply to produce one of the most natural, ’un-digital’ sounds it is possible to hear.But to me it’s a very strange thing to say, that it’s the reason "why" it’s got "un-digital" sound.
Cheers George