Where do I set volume control on NAD M51 DAC?

While there doesn't seem to be a clear exact figure, there seems to be a general consensus that -0 db is a bit to high. Noted by many through listening as well is measurements taken by Stereophile, where the DAC performed better at -10 db then it did at -0 db on their Benchmarks.

http://www.stereophile.com/content/nad-m51-direct-digital-da-converter-measurements#yAwtilFGs7kixtPK...

Also note that at -0 db, the voltage is slight bit above standard and a little of the volume seems to be the best route.

While true that digital volume controls can truncate the dynamics in music when applied to significant degrees, the NAD M51 has a 35-bit over the more typical 32-bit digital volume control implementations, giving it a bit more room before it begins to truncate the digital signal amplitude.

During the measurements via Stereophile, the small amount of overdrive that won't be any issue for nearly any premap, had increased the noise floor of the DAC notably. When lowered to -10Db, it was able to achieve 21-bits of genuine resolution across the audio band. I still believe that M51 is a benchmark for digital volume control implementations, I would agree that too much digital attenuation will prove detrimental to the audio signal.

I don't think those figures are correct as the NAD has a different stepping than one might assume. I know the actual top output is 2.375V SE and double that for balanced. -10db is just ten steps from 0db and the DAC can go to -55db before actually truncating a 24-bit file. While I can't say the exact voltage, I am sure the voltage is far closer to 2V at -10db than 200mv. This volume control is from a digital sense 210db in range.

Between the technical measurements and number of user indicated preference, the range that most prefer is between -6db to -10db. If you have a good preamp setup, it won't present any issues.