Audio Note DAC 4.1x Balanced

The DAC 4.1x Balanced is the standard AD1865-era Level 4 converter, distinct from the chipless IZVOR resistor-ladder version sold alongside it. It has no oversampling, no jitter reduction, no noise shaping and no re-clocking; the data stream is simply reformatted and all filtering is done in the analogue domain. Conversion uses the 18-bit Analogue Devices AD1865 chip, with matched 80% nickel super mu-metal filter coils. The balanced output stage is an upgraded M6 line stage on 5814a and 6463 double-triode valves, coupled to a 33:1 copper-wound output transformer on a High B C-core, feeding both unbalanced and balanced connectors. A dual-channel double-choke valve-rectified supply powers the design.