iFi’s SilentPower range aims to banish mains-related noise in your audio/AV system

iFi SilentPower DC Blocker and GND Defender
(Image credit: iFi)

iFi's collection of bijou audio devices for home and portable use needs no further fanfare from this publication (but do check our reviews of the iFi Zen Can, iFi Zen Phono and iFi hip-dac for starters if you haven't been introduced), but the Southport firm also makes a range of accessories to tackle common issues that affect the performance of audio systems.

The all-new SilentPower range is iFi’s latest collection of specialised ‘audio enhancers’ and is designed specifically to deal with mains-related noise. The range consists of four products at launch: the DC Blocker, the GND Defender and a pair of IEC power cables called Nova and SupaNova. So let's get stuck in.

iFi SilentPower DC Blocker

(Image credit: iFi)

The DC Blocker and GND Defender look similar – they both measure 68x37x32mm – but they are designed to tackle different problems that can both result in an audible hum. They connect to the power inlet at the rear of any audio component, with your power cable attaching at the other end and they can be used individually or together, depending on the issue (or issues, see main image) you're attempting to solve.

The DC Blocker's main objective is to eradicate ‘DC on the mains’ – a problem most of us are familiar with since it results in an irritating transformer hum. To backtrack a little: in theory, the electricity we draw from the sockets in our homes should be pure AC – a perfectly symmetrical sine wave alternating between positive and negative phases. However, life isn't perfect. This AC voltage is affected by small amounts of DC voltage (present in our mains supply for various and complex reasons) which can cause the AC waveform to become asymmetrical, an effect known as DC offset. The AC transformers commonly used in home audio equipment cannot tolerate the presence of significant levels of DC voltage without being compromised. Less than 500mV of DC – typical in an average household electricity supply – can be sufficient to cause toroidal transfers (the kind often found in amplifiers) to become saturated, which adversely affects sonic performance and may cause that audible mechanical hum.

Enter then, the DC Blocker. iFi states that it is capable of cancelling more than 1000mV of DC voltage, thereby correcting the DC offset and rebalancing the AC sinewave. Furthermore, it does this ‘intelligently’, adjusting its performance according to the level of DC detected.

iFi SilentPower GND Defender

(Image credit: iFi)

And so to the job of the GND Defender. Ever hear a hum or buzz through your speakers? You may have a ground loop problem. This occurs when two or more audio components in a system are connected to a common ground (or earth) point via different paths – if two different wall sockets on the same circuit are used to power different components in a single audio/AV system, where the components are connected via electrical (as opposed to optical) signal cables, for example.

If a ground loop issue exists, the GND Defender aims to resolve it by disconnecting the loop running through the connected component. By using one or several GND Defenders in a hi-fi system, iFi says that owners can ensure all components are connected to a common ground via a single path, which the should eradicate the resulting hum through the speakers.

Interference caused by ground loops can also affect picture quality in AV systems, resulting in issues such as visible scrolling bands. So the GND Defender offers to help solve this problem, too.

Both the DC Blocker and GND Defender have a voltage rating of 90V to 240V, so they can be used all over the world too.

iFi SilentPower Nova power cable

(Image credit: iFi)

On to the Nova. iFi has never made an IEC mains cable for home audio components in its nine-year history – until now. The Nova is billed as a specialised power cable with a high-end construction that belies its affordable price point, promising a "serious upgrade over standard mains leads that imbues sound with greater clarity, space and definition".

The Nova incorporates five conductors, each made from heavy-gauge, continuous-cast OFHC (Oxygen-Free High thermal Conductivity) copper. Two pairs of live and neutral conductors are arranged either side of the grounding (or earth) conductor, which is positioned at the centre of the cable – a design iFi calls Ground Zero.

A further pair of air-dielectric delineators (polymer matrix tubes filled with air) are arranged either side of the earth conductor, keeping the two pairs of live and neutral conductors apart whilst promising to improve the cable’s overall dielectric performance and constructive solidity.

Each individual live and neutral conductor sports multiple layers of insulation and shielding, too. The cable is completed with a tough yet flexible polymer outer sheath and iFi’s "audiophile-grade" connectors, with oxygen-free copper conducting pins coated in tarnish-resistant 24ct gold.

The sophisticated mix of materials and construction completes a power cable boasting constant impedance and superior rejection of EMI/RFI, maintaining the purity of mains electricity feeding each component in an audio or AV system. And although iFi is quick to state that the effect of this cable on sound quality is significant when used on its own, it combines brilliantly with iFi’s PowerStation mains-conditioning bar.

iFi SilentPower SupaNova

(Image credit: iFi)

Lastly, the SupaNova active power cable takes the Nova and adds a cylindrical housing part way down its length. This cylinder contains Active Noise Cancellation II – the latest version of iFi’s proprietary noise-busting tech – in combination with advance-filtering components.

iFi's approach to noise cancelling in cables uses inverse noise current to cancel out the noise in the mains signal. (Yes, comparable to the tech in noise-cancelling headphones).

iFi says that by combining the Nova’s sophisticated construction with Active Noise Cancellation II, the firm has delivered a do-it-all clean-power cable solution without the need for a separate mains conditioning device.

Sonic improvements promised by the SupaNova power cable include greater clarity and definition plus enhanced dynamic range.

iFi’s SilentPower range begins launching this month. The DC Blocker and GND Defender are available now, while the UK-plug versions of the Nova and SupaNova arrive in July. The DC Blocker is available for £129 / AU$189, the GND Defender costs £99 / AU$164, the Nova will be priced at £169 (1.8m cable) and the SupaNova will have an RRP of £349 (1.8m cable).


Read all our iFi reviews

See our pick of the best audio cables 2021

...and the best speaker cables 2021: budget and premium audio cables

Becky has been a full-time staff writer at What Hi-Fi? since March 2019. Prior to gaining her MA in Journalism in 2018, she freelanced as an arts critic alongside a 20-year career as a professional dancer and aerialist – any love of dance is of course tethered to a love of music. Becky has previously contributed to Stuff, FourFourTwo, This is Cabaret and The Stage. When not writing, she dances, spins in the air, drinks coffee, watches football or surfs in Cornwall with her other half – a football writer whose talent knows no bounds. 

  • abacus
    Cannot find any technical documentation or test measurements on their website, which is the first red flag.

    The voltage in the UK is 230V -6% +10% (i.e. 216.2 V – 253.0 V) so they do not meet the requirements for the UK market.

    The picture shown, shows that there will be an increased strain on the equipment socket thus causing loosening of the contacts over time and creating serious problems in the future.

    If you do have a problem (99.9% only think they do) get a professional in, not buy some product designed to make a quick buck.