Etymotic 2.5mm Balanced cable - impressions and comparisons:
Cables. Do they make an audible difference? Single Ended (SE) vs. Balanced?
Those subjects are often polarizing and cause audiophile debates…
Today, I am posting my personal impressions and opinions on Etymotic own 2.5mm balanced cable for IEMs with user-replaceable cable (ER2, ER3, and ER4 series).

For my tests and comparisons, I chose to use the ER3XR. To be able to compare SE vs. balanced on the same source (that support both) – I used FiiO BL35 (3.5mm male to 2.5mm female adapter).
Source used:
HiBy R6 DAP using its 2.5mm balanced headphone jack with the balanced cable plugged in directly, and using its 3.5mm SE headphone jack with the FiiO BL35 adapter.
Package and accessories:
That one is simple. Inside the tiny package is just the balanced cable itself. That is it.
My only comment here: I wish it came with a small zippered case, like the ER2/3/4 or MK5 IEMs. Why do I need a case for a cable? So I can use it to store the SE cable that came with my ER3XR, after swapping it out in favor of the balanced cable.
Build Quality, Fit and Comfort:
The balanced cable looks and feels identical to the stock ER4SR/ER4XR cable, except for the plug (obviously) being 2.5mm balanced instead of 3.5mm SE.
Strangely enough, at the time of writing this (Apr. 2021) – replacement stock cable is $10 more expensive (at $80) than the balanced cable (at $70).
You can expect the same high build quality. Same splitter and twisted wire pair from the splitter to the MMCX connectors. Same materials and thickness.
Balanced cable compared to ER3XR stock cable:
I do not believe the balanced cable sounds better, when used as SE (with the FiiO adapter). Some people with golden ears might claim they hear a difference – I am not saying they’re wrong, but the difference would likely be
very small.
The balanced cable is a little thicker, has nicer splitter and feels better build quality overall. Also, it is less prone to getting tangled.
Balanced cable compared to ER4SR stock cable:
The balanced cable looks identical to the stock ER4SR cable, with the exception of the plug being balanced 2.5mm instead of SE 3.5mm.
I am convinced even golden eared people won’t be able to tell the difference this time around (when used with SE source)!
So why should I buy a balanced cable if there is no audible difference?
Mind you my claims above were based on using the balanced cable with SE 3.5mm source. That changes when using the balanced cable with a real 2.5mm balanced source (such as my HiBy R6 DAP 2.5mm headphone jack).
The first thing you’d notice is… your IEMs are LOUDER now! That is caused by the fact that balanced sources have more power compared to the same source in SE output.
In many cases, and that is specific source dependent – the sound stage feels wider / bigger, and the instrument separation gets better. Many sources also achieve "blacker background" (lower noise floor) when using the balanced output.
In summary: balanced output vs. SE output is source dependent, and in
most cases it sounds better! You buy a balanced cable so you can take advantage of this superior output option.
Conclusions & recommendations:
- If you have (or consider buying) a source with balanced 2.5mm output jack – definitely buy a balanced cable! You will improve your sound overall. By how much? That depends on the quality of your balanced source.
- If you have ER4SR or ER4XR and no balanced source (or plans to get one) – don’t bother! You will need an adapter, and the sound would be identical.
- If you have ER3SE / ER3XR / ER2SE / ER2XR and no balanced source – consider this cable as a "look and feel" upgrade from the ER3/ER2 stock cable. You will need an adapter for SE output, though.