There should be no noise at all on the DC output of a high quality PSU such as Pauls.

My thought on a DC lead would be to use something screened.

Rather than trying to cancel out any noise the cable picks up from the atmosphere with a braid, stop anything getting in to the cable with a screen.
The high quality PSU should be a clean DC output anyway.

If Anyone is interested in experimenting, the cable used in my DSP 1.0 power cable should be ideal. ( just ask if interested)
A length of this with suitable connectors.
http://markgrantcables.co.uk/shop/in...products_id=47
2 x 1.0 mm twisted cores and lots of screening (the screen would need to be earthed at the PSU end in the XLR etc)

I have a few customers that use the DSP 2.5 power cable to feed this PSU and none that bought for this have returned them, so maybe it works
http://markgrantcables.co.uk/shop/in...products_id=69

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