Comments from Jeff Zhu :-
".....I can’t say it’s 1 or 2 DACs inside. Physically, it is 1 DAC module, but it works in 2 different modes. Each mode uses different part of the module and also shared some parts. Spring is a 24bit DAC, bit23 is msb (most significant bit) and bit0 is lsb (least significant bit). Yes, you are right, more bits can be used for digital volume control. But Spring is a pure DAC without digital volume. Actually digital volume is no match for a good resistor attenuator. That’s why we need a dedicated pre-amp, rather than use digital volume in a DAC....."
".....I can’t say it’s 1 or 2 DACs inside. Physically, it is 1 DAC module, but it works in 2 different modes. Each mode uses different part of the module and also shared some parts. Spring is a 24bit DAC, bit23 is msb (most significant bit) and bit0 is lsb (least significant bit). Yes, you are right, more bits can be used for digital volume control. But Spring is a pure DAC without digital volume. Actually digital volume is no match for a good resistor attenuator. That’s why we need a dedicated pre-amp, rather than use digital volume in a DAC....."