The M scaler will perfectly preserve distortion and noise that's on the recording, within the bandwidth of the recording. So the ADC noise from a 192kHz recording, which increases above 20kHz and peaks at 96kHz will still be there M scaled or not; and this noise will increase noise floor modulation in the DAC, so it sounds better to remove the noise, and that's the purpose of the HF filter. So M scaling or not makes no difference to the benefits of the HF filter. As too the 16FS or 256FS WTA filter 2 choice, then the warmer sound of the M scaler would make selection of the WTA 2 even more attractive; also being able to hear starting and stopping of notes with WTA 2 is more apparent too with the M scaler.