7)
The VIVACE DPP uses an enhanced input stage structure in order to increase linearity. Just to recap: the first (and very important) stage following the DAC chip is an open loop design using no feedback at all. While an experienced circuit designer should have no difficulties in designing a stage with low distortion or with low noise, it really is a challenging task to design a circuit delivering both at the same time. With the VIVACE DPP, we pushed the limits even further.
The distortion figure of the VIVACE basic is around 0,006% … 0,008% THD, showing some statistically variance due to the used JFET. The enhanced stage has a consistent THD figure of 0,001% @ 0dB. Remember: the usual stage designed around an operational amplifier (OP) like NE5534/32 will give you even better THD than this and reasonable low noise but at the expense of an unsatisfying sound quality due to the overload action in the feedback loop.
So, how does the enhanced stage sound compared to the fundamental structure? Small wonder, the difference is almost negligible due to the fact that the VIVACE DPP circuit is a tweak of the VIVACE basic circuit. While the VIVACE basic sounds sweeter, the VIVACE DPP is clearer and even more revealing. This is especially important when playing high resolution files, where masking effects of the analog stages flattens the sound.
8)
Prior to processing the S/PDIF signal in the actual DAC circuit, the two coaxial S/PDIF inputs pass through a jitter attenuator stage consisting of a PLL and highly stable quartz oscillator. If you see the circuit as black box, S/PDIF comes in on one side and leaves again as S/PDIF on the other site. While the actual sample rate and the bit depth are retained, the timing (jitter) and the stability of the flanks improved by an order of magnitude. Please note, no sample rate conversation is used, as this may alter the sound! I like to mention this fact, because most jitter reduction devices rely on sample rate conversation. As described elsewhere, a sample rate converter “converts” correct samples with the wrong timing into wrong samples (amplitude) with precise timing.
