Quality Power Cord

Try the Audioquest NRG4. Good build quality, quick break in, balanced sound for under $500.

Contact Bob Neil at Worldwidewholesales.com and look into a Hidiamond P3 powercord. Best in its price range x2. Amazing customer reviews. Great guy and extremely educated in the field.

Not surprisingly, out of 12 responses so far in which specific recommendations have been made, by my count 12 different power cords have been suggested (although some more than once).

It appears that the NAD C 356DAC, which is an integrated amplifier that also provides a DAC function, is somewhat unusual in that its IEC connector omits the safety ground pin. Presumably it can do that by virtue of double-insulating the internal AC wiring. But for that reason among others, I would be hesitant to extrapolate the results you are likely to obtain with specific power cords from experiences others may report using those cords on other kinds of components. And perhaps the lack of a safety ground connection has something to do with why the Signal Cable you tried performed poorly.

Lowrider's suggestion of the Cable Company is a good one, IMO. If they have already gotten back to you and were unable to make an application-specific recommendation that gives you confidence, you might try a number of different cords via their lending program.

Regards,
-- Al

Excellent suggestion from Bacardi on 11.9.15. I purchased a used Hidiamond P3 from tweek geek for less than $400 and was surprised to hear how good it was. My second choice would be a used audience powerchord e for under $400.00

AL, that's good research on the IEC.
Would a PC with a Screw-off ground pin perform with satisfactory results on the NAD C356DAC?

The Pangea Audio AC 14 XL is a quality cable and has such a feature.
http://www.audioadvisor.com/prodinfo.asp?number=PGAC14XLI