This is a review written by Chris Baillie August 2024.

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The scene

Some readers may have read Terry’s informative and comprehensive review of the muon pro filter system, which was published last February. Whereas Terry’s review is from the perspective of a potential buyer beginning their journey into the joyful world of network filters, readers will see that my piece is from me being the user of the eno2’s predecessor, which, as you may have guessed, is simply called the ‘eno’.

I have also reviewed and have access to other filters for comparison. The eno represents the genesis of the brand, which was set up during the ‘lockdown’ between two online friends, Richard Trussell and Rob Osbourne. The muon pro is essentially an upgraded eno, which, along with several other improvements, filters across all eight cores of the ethernet signal, meaning it improves the performance of 1Gb connections. The original eno was designed primarily for 100Mb connections; therefore, filtering was only applied to four cores. Digital audio evolves faster than most areas of audio reproduction, and networked audio is currently an evolutionary hotspot; hence, the eno2, like its big brother, the muon pro, benefits from filtering across all eight cores and is therefore similarly beneficial with 1Gb signals.

Terry explained the whys and wherefores of the concept and potential necessities of network filters, such as those from Network Acoustics, in his piece on the muon pro, so I will not repeat them too much here, other than to say the eno2 system has been designed to target high-frequency noise at frequencies its makers know to have a detrimental effect upon the music we hear. I have read some reviews of this type of filter that suggest some audiophiles, and indeed, reviewers consider using filters such as the eno2 in place of a good network switch.

Such a view misses the point, as these two types of devices are there to solve different problems. As you will read further into my review, I am using the eno2 in conjunction with the Melco S100 switch. Network Acoustics make their own switch called the ‘tempus’, which is highly regarded, and I hope to test it soon.

Form Factor

One of my few criticisms of the eno was that it could be tricky to place in and around your equipment rack. Much of this frustration was caused by the short, captive output cable, which, in many cases, would result in the filter dangling behind one’s system or wedged behind a post of the equivalent rack. Thankfully, the eno2 is quite different in this regard, being a small box (10.5cm x8.5cm x 3cm) made from aluminium with detachable cables.

As I have learned from other designers of this kind of product, the density of the aluminium used to house the filter affects the performance; Network Acoustics told me it took them a long time to perfect this aspect. You can purchase the box on its own as a filter, but here I am testing the ‘eno2 System’, which includes two ethernet cables, one 0.75m and the other 1.5m, which are designed to complement the eno2 filter.

The eno2 cables are made from high-purity, oxygen-free copper conductors and are designed to reject noise. As is often the case with well-designed network cables, the eno2 is grounded at one end only, so naturally, it is directional. These cables are terminated with gold-plated Telegārtner Cat 8.1 connectors. They feel well-finished and are pretty flexible; I particularly liked the green leather cuff at the ‘receive’ end of each cable.

How Does The eno2 System Perform?

Let me first recall the initial impact that the original ‘eno system’ had upon my reference audio setup in late 2021. Prior to installing this filter system, I was no stranger to reasonably exotic cables, yet it is fair to say that the eno took my system of the time to a new level. Music via the eno system became less bound to the speakers and allowed my system to produce a soundstage that ‘floated’ around them. There was more detail, less hash and more definition; the only slightly questionable aspect was the sonic balance with this filter system in place was more ‘brightly lit’; I use this term rather than saying it sounded ‘bright’, which in HiFi terms often means brittle and harsh, which was certainly not the case here.

Perhaps the balance could be described as slightly lean in my experiences, although not unpleasantly so. These observations were made with the eno system placed between a Melco NA1/2 and Moon 280D streaming DAC. Since first installing the original eno, I have tried several other network filters at various price points. The only one I found to outperform the original eno filter was the more expensive CAD Ethernet Control, the review of which you can read here

So, whilst the eno still offered good value for money within the scheme of things, it was perhaps time for an update of this filter, which, if I am not mistaken, was the first product of its type to hit the market. Prior to installing the eno2 System, I had been warned that it may take up to 150 hours to ‘run in’. Despite this, I found the eno2 to be an immediate improvement above the eno. At once, the balance was darker, as in the top-end was less spotlit and the background blacker. The music possessed more natural warmth, and instruments sounded more solid. Despite this, the music possessed more life, immediacy and definition – so the proverbial win/win situation.

I have to say, in my case, via eno2, the soundstage extremities were better defined, with instruments better separated in terms of depth perception. Boards Of Canada’s Telephasic Workshop, from a CD rip of their classic album Music Has The Right To Children, sounded freer and more detailed through the eno2. For the unfamiliar, this track is an all-electronic affair featuring some strange noises which form melodies, which now leapt from the speakers. Toning things down a bit with Bob Dylan’s Oh Mercy (Mofi SACD rip) and comparing the track What Was It You Wanted, the music sounded sweeter, more detailed, more rhythmic, and the bass more defined and textured through the eno2.

The Moon 780D DAC I use in my reference system has a streaming stage built in called ‘Moon MiND2’; therefore, I have a choice as to whether to listen to music from my Melco N1-S38 server via ethernet or USB connections. In general, I found that whilst the music sounded ‘bigger’ and more spacious via the ethernet input compared to the USB input, the former lacked the sense of focus and inner detail of the latter. The eno2 system has balanced that situation, and I find the two methods of connection to be much closer, to the point that during the review period, which, due the the nature of the product, requires me to use the ethernet input, I have not felt the music lacked anything compared to the USB input.

So, using the eno2, I got to enjoy the aforementioned benefits of the ethernet input without missing what was good about the USB connection. Gone is the occasional slight splashiness of the top-end that was occasionally apparent when using the ethernet connection, which I had wrongly laid the blame at the door of the streaming stage in my 780D.

For the majority of listening, I positioned the eno2 system between a Melco NA1-S38 and the 780D. A Melco S100 switch feeds the data from streaming services to the Melco NA1-S38 server, which effectively acts as a second switch for cloud-streamed music, yet meant files stored on the Melco benefitted from the eno2’s magic.

Users are generally advised to place the eno2 between the switch and streamer. Still, I got the best results with the setup above, as I have an SFP connection rather than ethernet between my switch and the Melco. I spent one afternoon comparing the eno against the eno2 using my Chord 2Go/Hugo2 portable into a pair of decent headphones. The respective eno systems were connected to the same Melco S100 switch as the main system. Bob Marley’s Coming In From The Cold, from Uprising album (24/96 download) sounded bigger and cleaner, with the soundstage expanding in all dimensions via the eno2. Interestingly, the results were in line with those I experienced in my main rig. I find it fascinating that two completely different products can be affected by noise in similar ways.

Putting the eno2 up against filters in the sub £300 category demonstrated there are clear benefits to be enjoyed by spending more. Whilst the English Electric EE1 and Stack Audio Smooth Lan are both excellent products, music via the eno2 sounded more relaxed, fuller and more refined than via the EE1 and more exciting and dynamic than via the Smooth LAN. Comparisons between the eno2 and CAD’s Ethernet Control proved challenging to declare a clear winner as the Ethernet Control performs a secondary duty of removing noise from the ground plane, even if no signal runs through it; therefore, results will be dependent on the noise source inherent within the component it is used with. I find that the CAD can improve the performance of some components, even if they are not in the network path between the router and streamer, so whilst there are undoubtedly times when the eno2 sounds more focussed and lively than the CAD, in certain situations the CAD’s darker and more relaxed balance may prove more suitable for systems that need taming somewhat.

I achieved the best results with the eno2 performing filtering duties, with the CAD plugged into a spare socket in the Melco. I do not have a high-end TV, but I have found in the past that positioning a network filter between my switch and BT box produces surprising results: the pictures appear crisper and cleaner, with the sound quality of TV broadcasts benefiting similarly to music sources. The eno2 proved the best of the bunch here; even my ageing Panasonic TV could show the differences between each filter. Streaming The Union in 4k via Netflix, the eno2 produced a picture that was considerably cleaner and sharper than EE1 and its predecessor, and it was easier to see what was going on during darker scenes. The real shock, and I am not using the term lightly here, was what it did with the audio soundtrack. As my wife was sitting next to me on the sofa at the time, I asked her if she could hear any difference between the cables. She replied that the sound filled the room and left the speakers with the eno2 in the circuit, which was precisely what I heard.

I will add to this there was more detail, and the sound was subjectively more dynamic. I do not use an ethernet cable between my TV and BT box, but Network Acoustics warned me that if one is used, the eno2 should be placed between the streaming box and TV, as the latter will be the most significant source of noise on the ethernet ground plane. Note I could not test the CAD on the TV feed as it is too big for the socket on the TV box.

The Accumulative Effect Of Multiple eno2’s

Towards the end of the review period, I was sent a second eno2 sample, this time as the filter package sans input cable. The idea was to see if and by how much the addition of a second filter wrought worthwhile gains to my system and if doing so would prove to be good value for money?

I installed the second eno2 between my router and switch with a Melco C1 ethernet cable providing input duties. I streamed the first track from Lucy Rose’s latest
album, This Ain’t The Way You Go Out, via Qobuz (16/44). I had already listened to this album a few times whilst becoming acclimatised to a single eno2, where it had gained energy and focus and provided an enhanced emotional connection. The second eno2 further improved these areas, but instrumental separation also took a leap forward. Additionally the bass now possessed greater texture and had more bounce to it. Next up, I moved on to something heavier and denser via Deftones’ White Pony (Qobuz 24/96) and listening to track two, Digital Bath, before and after the additional eno2 filter. I chose this track as a single eno2 had cleaned up this murky mix a treat, showing me that despite some dynamic compression, it was far better produced than I had previously appreciated. Of particular note, the soundstage now expanded well beyond the speakers and the drumkit was given more space at the back of the soundstage.

The second eno2 added air to the top end and improved the timing, making it easier to follow the melody of each instrument. These improvements meant streamed tracks were now closer to the versions stored on my Melco’s internal storage drive. TV pictures took a second leap forward in terms of sharpness and apparent resolution with the second eno2, which was hard to miss but easy to enjoy. It may seem like overkill putting £2400’s worth of filters on a £150 TV box and a nine-year-old TV, but it worked well all the same.

So Should You Buy The eno2?

If you own a serious streaming system, based on my experience with the eno2, then the answer to the above question is a definite affirmative. After reviewing the eno2 for another publication, I put my money where my mouth is, so to speak, and bought one. Since the eno2 system arrived, music has sounded cleaner, more spacious, fuller, richer, yet more defined and involving.

For owners of high-end AV systems that watch streamed content, the eno2 is a must-have product. A great thing about buying from Network Acoustics is their 60-
day money-back returns policy, so as long as you can afford to keep the product, as I think you will want to, it really is the proverbial no-brainer. My experience post-installation of the second eno2 demonstrates that you don’t need to stop at a single eno2, as the second filter has helped bring streamed music to the highest level I have experienced at home.

An Essential Audition Award is granted in recognition of a products high performance but with a certain uniqueness that makes auditioning even more essential.

For the full specification of the Network Acoustics eno2 ethernet filter and system please see their website linked here