A modern dwelling isn''t the ideal place to get the best from your hi-fi. Fridges, televisions and other electronic appliance left on draw power that basically messes up our mains supply. Hi-fi and home entertainment products tend to work better at ''off-peak'' hours, such as weekends and evenings. The reason for this is less distortion through the mains supply - due to less people using electronic equipment - during these ''off-peak'' hours. Mains distortion falls into two categories: one of the mains supply itself and the other cause by all the components in an audio or video system. These two plug-in devices are designed to eliminate this distortion and noise from the supply. The hi-fi can be connected to them, or a source of distortion and noise such as a computer, fridge, light dimmer, etc. - preferably both.
The Kemp uses two types of filtering: Serial which uses a coil, and Parallel which uses capacitors. Together, they lessen distortion harmonics.
Tests with a mains noise detector first proved the KE-SNS plug actually worked. It''s worth playing around with the plug and trying different locations to see if there is any marked difference in the effect. For me the effective placement in the office was in the multiple socket mains distribution block itself. Sound-wise I found that the background decreased and music was slightly firmer focused. Instruments had a tad more clarity and solidity too.
The Iso Tek Isoplug is the entry level mains noise eliminator from the UK based Iso Tek. At £30 the Isoplug is cheaper - and much lighter - version of a plug-in mains filter. It uses the parallel filter design with a selection of capacitors and variresistors which ensure minimal noise between live, neutral and earth wires. It''s recommended for use near an offending appliance, but again playing around with placement is worth it and using the noise detector showed that the Isoplug did indeed eliminate noise to good effect.
As far as upgrading the system sound was concerned it worked well, maybe not quit to the extent of the Kemp Elektroniks version but there was still a subtle difference in the overall focus of sound.
Both are worth investigating (along with a noise detector - available from Kemp also, or other accessory manufacturers) if you take your mains seriously. It tens to affect your system more than you''d initially think - and remember that in high quality audio, source is everything!
The differences are subtle but definitely there.

published in: Hifi World, September 2002