The Advertising Standards Authority has slapped hi-kit supplier Russ Andrews for claiming its super-duper mains cables could reduce radio interference on the power line.

According to the the company, its PowerKords reduce noise in the mains supply because they are wrapped up in woven conductors, enabling the company to charge more than a grand (£1,250) for what we would know as a kettle cable. The ASA disagreed, and upheld complaints that radio-induced interference in the mains supply isn't a perceptible problem, and that even if it was, the PowerKord couldn't reduce it.

Russ Andrews provided a host of anecdotal evidence, and one study, claiming that radio interference was a real problem, but undermined that argument by accepting that it was also a matter of opinion. Considering that combination, the ASA ruled that the effect was not proven, although it was implied to have been by the advertising.

The second claim, that the effect could be mitigated by using cables from Russ Andrews, also failed to stand up to scrutiny. The ASA consulted an expert who pointed out that the study, performed at Russ Andrews' request, only tested for half of the interference, and didn't bother connecting the earth wire, and that loading the wire with a 50 ohm resister was too far from typical usage to be worthwhile. That combination caused the ASA to conclude that the evidence "was not sufficiently robust to demonstrate that the PowerKords products were effective in reducing mains-borne Radio Frequency Interference".

The world of the audiophile is awash with products claiming to improve sound, but quality of hearing – and tolerance of degraded sound – is highly variable. Some listeners are happy to push their iPhone speaker all the way to 11, while others won't consider using an audio cable without a "direction of flow" indicator. Even among sound professionals there's huge debate about how far it's worth going before the law of diminishing returns kicks in, and there will always be people who'll take that additional step.

Mains supplies are one area that can reportedly make a difference*, but that's down to variations in the provided voltage rather than noise induced by nearby radio transmitters; a mobile phone will happily induce signals in an unshielded amplifier, but that's a long way from doing the same thing in a mains cable.

Not that any of that will stop some people spending a grand on a kettle cable. The ASA can only prevent the Russ Andrews making the same claims again, not stop fools with too much money splurging it on unnecessary kit. ®

* We're told... Your correspondent's brief career as a sound professional was curtailed when it emerged he has "no ears", and thus isn't qualified to comment.