Afaik it's not a problem with NuPrime DAC's to run the volume higher up in the range.
Even at 70 I believe you're still attenuating the signal, i.e. below unity gain.
In fact, it might be better, ultimately, to run at a higher level.
This line from the website implies that, for digital sources, the volume control operates digitally, so higher settings should be better, generally speaking:
"Therefore it make sense to best adjust the volume in the digital domain for digital signals, and use an analog preamp and volume control for analog inputs."
That said, the very next paragraph seems to contradict the previous statement somewhat:
"Our DAC-9 and DAC-10* have analog inputs without A-to-D conversion. We use a mixed analog and digital volume-control design. The digital volume control’s 0.5db steps are sent to the DAC for the best possible result. The DAC’s analog output and analog inputs from other sources then go through a switch-resistor network. The DAC's output is switched straight through with minimum resistance. For analog inputs, the switch resistor network provides the best possible result."
It's very clear that volume control from analog sources is managed by 'switch-resistor network'.
But the above two statements imply that, for digital sources, BOTH the 'digital volume control' and 'switch-resistor network' play a role. Confusing.