Hardware Reviews

CAD USB Control opens up the sound

CAD USB Control opens up the sound https://the-ear.net/

CAD USB Control noise reducer

Us audiophiles are supposed to like noise, but the wrong kind of noise can be the bane of our lives. The more ‘tech’ we hook up to our mains supply, the more wi-fi devices we have in our homes, the more difficult it can be to enjoy the systems in which we have invested so much of our earnings. Thankfully, companies such as CAD take the fight to such evils so that our systems can keep on delivering sonic smiles. Regular readers of The Ear may have noticed that CAD’s GC1.1 Ground Control was included in our Best of 2023 awards as my choice. Whereas the GC1.1 and its bigger brothers in the GC range are designed to remove noise from various sources, such as mains blocks and analogue and digital input sockets, the USB Ground Control specifically targets noise caused by USB circuits. My first response to this idea was that a properly designed USB circuit might benefit far less from such a product, but CAD’s Dave Denyer revealed that research suggests that the more high end the product, the greater the benefit of the USB Control.

Unlike the GC product range, which have cables running between a component and a large grounding box, the USB Control is simply a USB A plug with a black acrylic body behind it that houses the secret sauce. You can plug the USB Control into any unused USB socket on a component within your system but it works best with those that do not output the audio signal. I assumed that this would involve a digital source. However, many analogue components, such as amplifiers and phono stages, contain USB sockets to facilitate software updates, the circuitry of which will likely cause noise which is detrimental to the performance of that component. It is possible to use multiple USB Controls in one system. My Melco N1-S38 server alone has four unused USB A sockets, so at £675 per unit, the costs of totally ridding my system of unwanted nasties could soon add up. So the trick is to experiment with each socket and use it on the one that delivers the most pleasing results.

CAD USB Control opens up the sound https://the-ear.net/

Does less USB noise mean more music?

My first experience with the USB Control was with a prototype, which brought positive results when used in a spare socket of the Melco NA1/2 server that I used at the time. According to CAD, the production version does the job more effectively. The NA1/2 has since been replaced by Melco’s flagship N1-S38, which has a far superior USB stage to the NA1/2. Because of this, I was somewhat doubtful that the USB Control would be able to improve upon the already stellar performance of this server/streamer. It took just a few seconds of Agnes Obel’s Dorian to disprove such misconceptions. The comparisons in this review were made using a pair of recently launched speakers called the Etude 5. These large floor standers, whilst impressive, did not give me a soundstage that would float free of the cabinets as my usual Totem Forest Signature speakers do. The first thing that became clear was that the soundstage was bigger and the music was less confined to the speakers, not quite as I enjoy via the Totems, but things were certainly heading in the right direction. I also noted that the music possessed a darker background, presumably due to the reduction of digital ‘hash’. These initial observations were made with the USB Control plugged into the Melco’s expansion socket for external hard drives. We then plugged it into the unused USB 3.0 input/output socket – the USB 2.0 socket is optimised for musical performance, so this feeds a CAD USB II-R cable connected to my DAC. This brought a little more detail and body to the music. I pondered what a USB Control in each socket could deliver.

Next up was a favourite of mine, Dust Swirls In Strange Light, from The National’s 2017 album I Am Easy To Find. With the USB Control working its magic, the female choir’s vocals had more body and, as with the Agnes Obel track, the soundstage was larger in all dimensions and I was less aware of the speaker’s cabinets. The track starts with the choir over quiet piano notes before being joined by bass and drum parts, which the USB Control helped deliver with greater precision, weight, and drive. As the track builds, it becomes a polyrhythmic extravaganza. Those polyrhythms were now much easier to follow, and the time signature of each instrument and electronic sequence was laid bare.

CAD USB Control opens up the sound https://the-ear.net/

Having spent more time listening to the system CAD USB Control, the results were consistent. With it inserted into a spare USB port on my Melco server, the music sounded more colourful, possessed superior timing qualities and better resolved fine details. The extremities of each soundstage dimension were more definite, and the music appeared less tied to the physical dimensions of the speakers.

Music was off the menu one evening as my wife reclaimed the living room to watch TV. I remembered our BT Vision box has a USB socket and I am pretty sure it is just for software updates, etc. Regardless, I plugged USB Control into the BT box, which we use to record off-air programs and stream from catchup services. Who knew Silent Witness could deliver a 3D soundstage? It can when CAD’s USB Control is working its magic. Not only this, but the picture was slightly sharper. I will make comparisons using my Oppo Blu-ray player next, but in private, as this is supposed to be a hi-fi publication. I am sure you get the picture, if you pardon the pun.


As with CAD’s award-winning GC1.1, the USB Control hits noise where it hurts, significantly improving your musical enjoyment in the process. Whilst £675 for what looks like a USB thumb drive will raise eyebrows amongst those new to the concept of such devices, assuming you have already got the basics of your system right, such as the mains supply, cables and supports, then adding a USB Control may be the best upgrade you can make without having to find extra shelf space.

CAD USB Control opens up the sound https://the-ear.net/

Jason’s opinion

I also tried the CAD USB Control and started off at the opposite end of the equipment spectrum with a rather ancient Macbook running nothing more exciting than iTunes. Whether the CAD device would have had a different effect with more sound quality oriented software is hard to tell but my experience indicated that what CAD says about the USB Control being more beneficial with better gear proved to be true.

With the Macbook the benefit was an increase in depth and three dimensionality of image alongside an increase in ease, the sound was more relaxed but not hugely so. Trying the USB Control with my Melco N10 which was connected to an Auralic Vega G2.2 DAC via a Mutec MC3+ USB reclocker resulted in far greater gains, it really was a wow moment. The main change was to image solidity as with the PC but the increase in projection was far greater with considerably more space and depth in the soundstage.

The CAD achieves this by reducing the noise floor so that more of the quiet detail that defines the image can be heard, the Control USB does a fabulous job of reducing noise so that this can happen. With Radiohead’s Decks Dark ( A Moon Shaped Pool) you can hear so much more of the harmonic and reverberant character of the production that the soundstage appears to be further in front of, outside of and behind the speakers. This clarification of what’s going on also improves timing because attack and decay is better defined too.

CAD USB Control opens up the sound https://the-ear.net/

I spotted a USB port marked HDD on the back of an Auralic Aries G2.2 streamer so gave that a go with the CAD stick. Here the changes were similar with a sense of calm being introduced alongside enhanced dynamic range, presumably because the reduction in noise floor meant that quieter sounds were revealed. With a string octet piece (Mendelssohn Octets, Locrian Ensemble) the benefit was greater still with the sound totally escaping the speakers and coming into the room, it is as if the instruments have more space to breathe. To top this off I put a second USB Control into the Melco providing the signal, this was a very good idea as the presentation became dramatically more relaxed and refined. It’s very difficult to get a system to reproduce the subtlety of violins, violas etc but this got me as close as I can recall hearing. I have to say that although the CAD USB Control is small the benefit it brings to high quality equipment is genuinely big.


Type: USB noise reduction device
Size HxWxD: 12 x 24 x 58mm
Weight: 15g
Warranty: 2 years

Price when tested:
Manufacturer Details:

Computer Audio Design
T +44 203 397 0334


noise reduction device


Chris Baillie, Jason Kennedy

Distributor Details:

Computer Audio Design LLC
T +1 541 728 3199

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