Effect Audio Code 51 & ConX

Let your IEMs shine.

PROS: Lifts IEM performance to their peak without adding color of its own, increases transparency significantly, maintains a neutral and accurate tone, adds a sense of realism, superb ergonomics and excellent build quality.

CONS: If you have to ask the price…


I would like to thank Effect Audio for providing me with their Code 51 flagship cable in exchange for my honest opinion. No incentive was given for a favorable review.

Code 51
  • 24AWG
  • Selected Premium UP-OCC Material
  • Gold Plated Silver / Silver Gold Alloy / Palladium Plated Silver Hybrid
  • Golden Ratio Dispersion Multi-sized and Multi-Bundle Stranded
  • Individually Enamelled Strands
  • Superior PSquared / P-EA Plug with Titanium Casing
  • Exquisite Titanium Y-splitter
  • EA UltraFlexi Insulation
  • Price: starting at US$2,388.00


Effect Audio was founded by Zou Suyang back in 2009 and Code 51 is Effect Audio’s 10th anniversary flagship cable released (of course) in 2019.  Now, before I start this review, I have something of a confession to make. While I have always enjoyed tinkering around with cables and can at times obsessively roll different cables to explore synergy and find the best match for specific IEMs, I have not been super keen on dipping into US$1k+ flagship cables. Partly because I have always been a bit concerned by the law of diminishing returns with respect to cables. At the same time my experience with flagship cables has not been super positive.

The first is of course inherent to this hobby and something that will be different for each person. We all invest different amounts of money into this hobby and where any of us finds their sweet spot and their limit is entirely personal. For those of us who refuse to compromise and have the budget to do it, there are now options well beyond the price point of Code 51. Indeed, I have friends who rotate those like they are trying out different candy. I don’t have deep pockets like that and so my reluctance was always more about not feeling like I was the right person for the review, but darn it, I am insatiably curious and so this was pretty much inevitable.

The other reason however was more important. I simply was not very impressed by the flagship cables I tried in the past. Some I found too dry and analytical for my preferences, lacking the naturalness I prefer and not really engaging me with the music. Other cables sounded great with wonderful naturalness and excellent transparency, but were ergonomic nightmares that felt like I was trying to wear a garden hose. Call me pedantic, but I found that completely unacceptable at such a high price point. Then again others managed to combine the two, meaning I was not getting the synergy I was after and I needed to wrestle the cable at every turn just to keep the IEMs in my ears. No. Nope. Not doing that again.

Enter Code 51. For a number of reasons, I found Code 51 more compelling than any other flagship cable I knew. The descriptions and impressions I came across suggested to me that Code 51 could be combining all the characteristics that I value. I suspected that Code 51 had the ability to elevate the performance of IEMs in a unique way, doing what other flagship cables do in a clinical way, but instead doing so while retaining a natural tone. Code 51 was at the same time a cable by Effect Audio, which meant I could trust the ergonomics to be among the very best on offer. Finally, Effect Audio just released their ConX interchangeable connectors and that would make Code 51 uniquely versatile for a flagship cable. Time then for a closer look.


Time… [hmmm] then… [nope] for… [oh there] a closer… [come on] look… [open up you *beep*]. ROUND 1: Box 1 – Wyville 0. I will spare you the transcript of the next 37 rounds before I finally managed to open the box. The black box that Code 51 comes in has a perfectly fitted lid that slides over the box perfectly and fits perfectly tightly. This looks perfect and indeed is perfect for display, but it is also perfectly frustrating, as there is nothing to grip for getting out the bottom side and it won’t easily slide out under its own weight either. Perfect for a nice long unboxing experience.

[Edit to cut out a 45-minute lesson on “How to swear in Dutch.”]

And there it is! The y-split… So, after the painstaking process of finding creative new swear words while waiting for gravity to do its magic, I have to admit it is a slight anti-climax to see just the y-split. Don’t get me wrong, it is a unique presentation and the y-split is a beautiful piece of engineering, but the wires of the cable are completely hidden and those really warrant a sparkling display when you open up the box. Same for the gorgeous titanium plug and ConX connectors. All quality parts that I would have liked to see on full display when opening the box. At this price point, I might have opted for displaying the entire cable resting comfortably in a bed of Vantablack fabric to draw all the light towards the cable itself.

Honestly, I am being a bit silly here. Overall, the presentation and the unboxing experience is very nice. The cable on top (very important, the good stuff first), then a metal card with the serial number and below that layer sits a wonderful case. The case is the perfect size and I love using this type of round case. Of course, it is all about that gorgeous cable, as most people will forget about the packaging as soon as they see that stunning piece.

Build quality.

Build quality is what I expect from Effect Audio, extremely good and I think that with the parts of Code 51, Effect Audio have achieved a step beyond their usual premium quality. Using titanium is a direct way to this reviewer’s heart because I love that material. It is light, extremely durable and a bit less “bling” than chrome, which (to me at least) feels more refined.

The y-split always struck me as big and clunky in the pictures I saw, yet it is not anything like that in real life. The y-split is great size for the cable and the titanium keeps it nice and light, while giving just enough weight to pull down the cable a little and not too much, which I always like. The plug too has some titanium details, which I think looks superb paired with the carbon. The connectors are the new ConX, which makes Code 51 highly adaptable for use with a large number of IEM connectors (more on ConX later).

The ergonomics are as expected, wonderful. Effect Audio have always been good at this, even with their 8-wire cables. Code 51 is a 24 AWG cable and so thicker than the more usual 26 AWG cables. When you wear glasses, it is noticeable that there is a little less room behind your ears for both, yet that is all there is to be said about it. Once I have the music going and I go about whatever it is I am doing, the ear guides stay comfortably in place and the rest of the cable is super supple so I don’t feel it ever gets in the way. In the context of my experience with TOTL cables, Code 51 blows a lot of the competition away in this respect.


ConX is Effect Audio’s solution for the constantly changing types of IEM connectors on the market and for allowing users with multiple sets of IEMs to use the same cable for all irrespective of their connector type. This is very useful, as I can imagine that people who have invested a lot in their IEMs and aftermarket cables can at times feel restricted to one type of connector. Being heavily invested in (for instance) a setup with 2-pin connectors, can prevent them from buying IEMs that use mmcx because of the additional cost of having to get cables switched over as well. Development of the system took six months and from what I understand Effect Audio managed to create these connectors while maintaining super low impedance.

I can’t test if/how the connectors effect the sound quality, but for practicality ConX works a treat. The connector shells have a thread on the inside that allows the connector head to be replaced by unscrewing and putting in a different type. The ConX set comes in two versions, one with two 2-pin and two mmcx connectors, and one set with 2-pin, mmcx, Ear and A2DC connectors. The Code 51 under review here came with the latter set, although I only have 2-pin and mmcx IEMs, so could not try out the other two types.

Changing between connector types is easy and can be done with the key that can be found in the bottom of the ConX box. It is a bit fiddly at times to use the key, but I also found it easy to do without. Surprisingly, I find that every time I changed between 2-pin and mmcx, the connectors always lined up perfectly and I did not notice any odd angle of the 2-pin connector. If it would be off, it could easily change how the ear guide sits relative to the IEMs and as such affect fit. No such issues occurred while I was testing.

Overall, the ConX system proved its versatility and durability so far. I had no issues with the connectors coming loose during use and did not experience any connection issues or such.

Page 2 – Source, Sound analysis, and Conclusions.

4 thoughts on “Effect Audio Code 51 & ConX

  1. Hi twister, thank you for your all round trusty review, I was wondering if Code 51 make a good pair with U18s in terms of expanding the sound stage and pushing the vocals forward? What character do you think Code 51 introduce to BA IEMs? Thanks.


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