Outboard DACs

There is one parallel between Audiolab's ES9038PRO-based 9000N network DAC and the ES9038Q2M-based Nu-Vista DAC tested here – both units clip at 0dBFs (full digital scale) with the 'Upsampling' mode switched on, the latter also needing to be switched off before the digital filters are enabled. The Nu-Vista DAC uses a 'low power consumption' version of the ES9038 – more typically targeted at portable devices – which has a lower specification, however the uniform ~0.004% distortion (20Hz-20kHz/0dBFs) is set by the 7586 nuvistors rather than the DAC. So too is the 102dB A-wtd S/N ratio and the increase in output impedance from a low ~12ohm midband figure to a significant 1.1kohm at 20Hz – expect some cable/amplifier sensitivity at very low frequencies. Under ideal conditions, the Nu-Vista DAC has a very slight LF roll-off amounting to –0.05dB/40Hz and –0.5dB/10Hz.

Low-level resolution is true to ±0.2dB over a 100dB range (and –0.5dB adrift at –110dBFs) while distortion just nudges below 0.001% over the top 30dB of the DAC's dynamic range [see Graph 1, below]. MF's '<100 femtoseconds' (<0.1psec)specification for correlated jitter refers to the clock and not the DAC whose datalines are potentially subject to modulation from any number of local sources. In practice, figures of 25-75psec are more realistic – this is still excellent, but the correlated sidebands [see Graph 2] are joined by low-level spuriae that increase the brighter the display setting [red spectrum, Graph 2]. Mute that big display for minimum interference! Finally, the Nu-Vista DAC's analogue stage offers a good >90dB stereo separation and 0.08dB channel balance (all re. 20Hz-20kHz). PM