IsoTek V5 Sigmas: “Highlight” in the lite-magazin.de test

In June 2026, lite-magazin.de tests the IsoTek V5 Sigmas mains filter and explains, in an extremely detailed listening test, the sonic benefits such a device brings to a HiFi system. Here we quote “only” the essence – but reading the full test report is definitely worthwhile:

“To find out what the V5 Sigmas does, we first start without it. In doing so, we make every effort to create the worst possible power supply conditions: we choose two of the cheapest three-way power strips, disastrously connect them one after the other in series, and also use only the cheapest supplied power cables for the components. We connect the devices without paying any attention to phase alignment.

We stream our opening track via Qobuz: Patricia Barber’s jazzy version of ‘The Thrill Is Gone’. The singer and pianist is accompanied by bass and drums – and actually, the playback already sounds pretty good. But the words ‘actually’ and ‘pretty’ mean: surely there must be more to it than that!

To turn this suspicion into certainty, we now connect all components to their designated sockets on the V5 Sigmas and start ‘The Thrill Is Gone’ again – and now the playback proves the song title wrong: the thrill is only really there now! Piano, bass and drums have a completely different presence.

The bass immediately provides a solid foundation. With the cymbal, meanwhile, the gentle stroke is enough to make the impact of the drum brush on the hammered bronze disc effortlessly audible, lending the song a great deal of atmosphere. The atmosphere of the song now unfolds all the better because the spatiality of the playback has also been significantly improved. Whereas the presentation previously seemed somewhat flat and stuck to the speakers, the image now has depth.

[…]

Let us switch from streaming to vinyl. Here we choose ‘Mary Shut The Garden Door’ by Donald Fagen – and when tracking the record groove and the resulting music playback, the improvement brought by the V5 Sigmas is even more pronounced. Here, the added calm and purity become all the more noticeable. As a result, the playback sounds even clearer.

[…]

We hear more, and therefore we understand more: the music is simply more fun. And this enjoyment is further enhanced here by the more sonorous reproduction and richer dynamics, the greater precision and the more defined bass.

[…]

To conclude the listening session, we replace the standard power cords used up to this point with a set of IsoTek power cables – and, as secretly expected, experience another performance boost across all disciplines. We notice it particularly in the finer details. Overall, the playback is even tidier, the bass once again more accurate, the precision slightly increased – and the imaging a little more airy. Wow!”