Russ Andrews (UK), a Meridian dealer, offers a week’s rental of the
Audio Prism Noise Sniffer, including one of their mains silencer’s for £35.
That’s considerably cheaper than buying your own device at £135 (inc VAT) that you would probably use once. The caveat is that the Russ Andrews device doesn’t have a digital readout, so you cannot objectively measure mains noise.
Maybe biased, but Peter at Russ Andrews stated that their
Evolution-300 PowerKord’s, when tested, improved the performance of their DSP5200SE’s and DSP3200’s.