One thing that the M33 does do in the analog domain is RIAA equalization for its MM/MC phono stage. According to Greg Stidsen, using DSP to provide the great amount of headroom (40dB) required for this wouldn’t have allowed them to meet their signal/noise target with the digital technology currently available. He added that they were still able to achieve a precision of ±0.2dB by using high-quality resistors and capacitors in the analog circuits. Whatever NAD has done in the analog and digital domains, Dire Straits’ Dire Straits (LP, Vertigo) sounded fantastic. In “Six Blade Knife” there was plenty of separation and imaging of Mark Knopfler’s unique finger-picking style on electric guitar, and of John’s Illsey’s bass guitar. And even though my turntable’s analog signal had been digitized by the M33 and then further DSP applied to that signal, everything in “Sultans of Swing” sounded exactly right. The M33 situated Knopfler’s guitar more centrally and not as far forward as it appears in “Six Blade Knife” and “Down to the Waterline,” slightly differentiating the presentation of the guitar on these three tracks.
from https://www.soundstagehifi.com/index.php/equipment-reviews/1480-nad-masters-m33-integrated-amplifier-dac