Metrum Acoustics Hex NOS Differential DAC

NOS
The Hex DAC is, according to Metrum Acoustics, a non-oversampling (NOS) filterless DAC in the strictest sense. This means that inside, including inside its mysterious* DAC chips, the PCM signal remains a PCM signal and it passes through the D/A process un-oversampled and un-filtered, as it were. Many of today's DACs, even some calling themselves NOS DACs, employ delta-sigma DAC chips that, among other things, oversample, interpolate, convert the PCM signal to a PDM signal (pulse-density modulation), and filter our precious musical data. Filterless NOS DACs skip these steps and some feel that the resulting analog signal sounds more analog-like as a result.