Problem
My NADAC gives once in a while distortion/clipping at the highest (critical) peaks/transients close to full scale
Solution
You may have connected the NADAC output (balanced) to an unbalanced input.
See here what is the difference between balanced and unbalanced.
Find here how to connect the symmetrical line out from the NADAC to an unbalanced input
Never attempt to short pin 3 (or pin 2) to Ground on NADAC DA's output, since the NADAC Line Out driving circuitry is symmetrical but not floating.
Furthermore, as Unbalanced Inputs are traditionally more sensitive than Balanced Inputs, the - 6dB Analog level achieved by using only one of the NADAC symmetrical outputs, will offer better signal level adaptation with less risks of overdriving the Unbalanced Inputs connected to the NADAC.
Related articles