This review page is supported in part by the sponsors whose ad banners are displayed below

As with all cables that come in, we first gave the Linebacker a few days to acclimate. For this we connected it to the wall with a length of Crystal Cable and at the other end to a passive Furutech TP60E power distributor. This fed a PS Audio PWT, a Devialet D-Premier used also as preamp and two Trafomatic Kaivalya monos. Speakers of choice were the Arcadian Audio Pnoe horns. The burn-in days were filled with background music. When the time came for the first serious audition, the Linebacker had just over 80 hours of filtering on its clock.

Dulce Pontes always is excellent to assess system quality. Her voice can be piercing and crack the enamel right off your teeth if anything is wrong. With the Linebacker in place, her Momentos album was pure joy. With it Senhora Pontes celebrated her 20th career anniversary (2010) and shows off  broad musical skills and tastes. Aside from genre-typical Portuguese guitar and piano there’s also bouzouki, bagpipes and even tablas in her musical entourage. The powerful use of her upper register is key to Dulce Pontes and on this mix of studio and live recordings with traditional fado and more eclectic excursions amply present. With the Linebacker in place the system refused to break up or create any harsh edges on her powerful high notes.

All follow-up albums from bass virtuoso Renaud Garcia Fons to trance-inducing Hadouk Trio depicted the same quietly ‘invisible’ background. Imaging was spot on without being unnaturally cut out. Individual instruments possessed a fair amount of air/space around them depending on recording and mixing techniques. When we eliminated the Linebacker and connected the power distributor via the Crystal Cable power cable directly to the gear, it traded the velvety backdrop for a more greyish version. Sounds and their placements were not as outstanding as before. They all blended more into the background and into each other. This was a nice proof of the Pranawire filter’s efficacy.

There would be more. As we still had the Blue Horizon Noise Analyser on hand, we could not resists to conduct an actual measurement. This analyzer makes that pretty easy. Just plug its captive power cord into any wall outlet, listen to the noise emitted through the little speaker and read the display. In our case the latter showed a fat 600 out of an abysmal 999 to point at a pretty noisy mains. As reported in our review of the Noise Analyser, for some inexplicable reason we also have a radio station freeloading on our mains spur which is perfectly audible over the Analyser’s speaker. If the Linebacker really worked as advertised, we should be able to get a lower reading. With our homebrew adapter cable we connected the Analyser to the Linebacker’s female Oyaide. And guess what? The reading dropped to a respectable 160, meaning a lot of HF noise had gotten filtered out for the remaining noise to measure safely within the ‘okay’ green zone. This substantiated a good deal of the Linebacker’s audible improvement. What remained was the radio reception. Was this then already the conclusion?

Not quite. There was more to the Linebacker albeit on the somewhat obscure side of the power issue. Aside from the neutral and hot lines almost all audio systems make use of a third power connection called protective earth or PE. As its name implies it was intended as protection against shorts. With PE a user should not be victim of shock or electrocution. A system with a PE connection grounds to our planet’s conductive surface. Next to protection PE is a means also for electromagnetic compatibility or EMC. According to Wikipedia, EMC is “the branch of electrical sciences which studies the unintentional generation, propagation and reception of electromagnetic energy with reference to the unwanted effects (electromagnetic interference or EMI) that such energy may induce. EMC aims to ensure that equipment items or systems will not interfere with or prevent each other's correct operation through spurious emission and absorption of EMI. EMC is sometimes referred to as EMI Control and in practice EMC and EMI are frequently referred to as the combined term ‘EMC/EMI’.”

Cool, ain’t it? In hifi we constantly struggle to get rid of EMI from sources like cell phones and their transmission towers, WiFi and what not. On top of that we use more and more computer-related devices which are notorious for EMI/RF radiation. What is done to match EMC standards? Manufacturers shield their equipment and said shield connects to the PE wire. This sounds great in theory but in practice isn’t great at all. As more and more equipment gets shielded and grounded through the PE connection, the latter’s original concept is altered.

PE was envisioned to form a low-impedance circuit for fault currents at the power system’s base frequency of 50 or 60Hz. Now more and more gear including cables is shielded and all these shields or screens connect to the PE. This results in an injection of currents not of the fundamental 50 or 60Hz frequency. The injected currents are of far higher frequencies and suddenly the PE wire no longer forms a low-impedance drain. Today’s use of switching power supplies for instance causes a huge injection of high frequency noise to the grid. Some say the grid’s PE is only designed as a safety measure and no longer operates for EMC purposes.