MIT make a range of 'Audio Interface Networks' that are essentially replacement leads for various applications. They all feature one or two moulded 'bulges' along their length containing various secret electronic components, which are claimed to improve audio sound quality in various ways. Leads are available to connect between guitars and amplifier inputs, as well as between the output of the amplifier and the speaker. However, the lead under review here arguably doesn't appear in the audio chain at all, as it is designed to replace any standard IEC mains cable. MIT say in their publicity material that it lowers noise, improves clarity, and provides greater dynamics. Bold claims indeed!
Although many people remain unconvinced, there are several mechanisms that can cause audio quality to be affected by mains interference. For a start, the purity of the incoming mains signal itself is often dubious, especially if you live near any factories, or in the depths of the country. We are also surrounded by RFI (Radio Frequency Interference), which can be picked up by mains cables acting like an aerial. A third source of mains interference can be other nearby digital equipment (such as computers and digital recorders) which emits stray RF signals.
The ZCord II aims to filter out any existing interference riding piggyback on your mains voltage, as well as stopping any further pickup along its length by using heavy‑gauge shielded cable. Although the theory is sound, you will only see an improvement in your audio quality if you are suffering from such interference in the first place. Ironically, it is often the very devices that may produce such interference that are particularly susceptible to its introduction from elsewhere. Samplers, CD players, DAT recorders, and computers may all (depending on the individual design) benefit from the ZCord II. So, did I notice any difference in my setup?
Many of the devices that I would have liked to have tried with it either had captive mains leads or wall warts, including both my DAT recorders, two power amps, and mixer. I tried it with my Akai sampler, my keyboards, and my PC, as well as a couple of CD players, and although I can't claim any revolutionary changes, at times low‑level detail did seem to be improved when playing CDs. However, it is impossible to perform quick A/B tests with a mains cable, at least without risking damage to the equipment concerned.
After hearing the significant difference when trying the MIT guitar leads, I must admit being rather disappointed with the ZCord II — it provides rather more subtle improvements which depend largely on the combination of equipment you have, and how susceptible it is to RF interference.
I am still a firm believer in the benefits of improving mains quality, and will carry on cleaning the pins of my mains plugs with wire wool. Despite being a convert to the cause, however, I do feel that the ZCord II is expensive at £135 — several other hi‑fi mains cables that claim similar improvements are available at prices between £25 and £100. This is definitely a try‑before‑you‑buy product. If you suspect that you are suffering from RFI then try the ZCord II instead of a standard IEC mains cable — you may be blown away by the improvements, particularly if you are surrounded by digital gear or in a stage environment. On the other hand, you may hear little or no difference at all. Martin Walker