best power cord for mccormack dna500

There's no such thing as 'best' power cord for anything. If it exists, then everyone will be using the same power cord.

It all depends what you're trying to achieve, power cord is just a means of 'tone' control, even though some manufacturers try to convince you that their PC are 'neutral', don't buy into any of the hype. The only way of ascertain 'neutralness' is via measurement. Unfortunately human hearings are not created equal, hence 'good' measurement does not necessarily translate into 'good' sound.

Hence when you seek advice on cables, it is best to describe what you're currently using in your system, and tell people what you like/dislike about your current system.

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Try several and sell the ones you don't like. I recommend Eichmann Technologies Series 2, or Tek Line Cables microReference

I used an Elrod Statement on my DNA-500 with excellent results. Its best to try several - maybe call the Cable Company(John is helpful) and get a few to try from them.
Good luck.

thanks