By Nick Smith, 18th September 2025
When was the last time you enjoyed a uniquely special audio experience?
Last year I reviewed the ISN H60s and immediately christened them my favourite earphones under $500. They were so good I later paid ISN to build a custom-fit set for me.
Why customs? It’s true that universal fit IEMs are incredibly comfortable and effective at blocking out noise these days… yet the gap between how well they do both is still inferior to CIEMs.
So when ISN recently offered to send me a pair of EBC80s in exchange for my thoughts I asked if they’d supply a custom version and to my delight they agreed.
I say delight because there’s a special joy listening to earphones built specifically for YOU that nothing engineered to fit “most” ears can fully replicate – and if you’ve never owned a pair of CIEMs before nothing would give me greater satisfaction than this review convincing you to take the plunge!
Now, let’s begin.
Packaging
The USD $699 ISN EBC80s (+$100 for custom version) arrive in fairly small, nondescript cardboard box.
Inside is a compact faux leather case, 9 pairs of silicone eartips if you purchase the universal version, and your choice of one of three stock cables – the OCC copper ISN C2, hybrid copper & silver-plated H2, or silver-plated S2. Each cable comes with detachable 2.5mm, 3.5mm & 4.4mm plugs.
It’s a fairly spartan bundle given the pricepoint, so it’s quite clear ISN is prioritising devoting as much of the purchase price towards the IEMs & cable, rather than delivering a lavish ‘unboxing experience’.
Ergonomics
Normally this is where I’d discuss construction quality & comfort, but this is a special case – a set of custom earphones built specifically for my ear geometry.
There is something very special about CIEMs and if you’re yet to discover the magic then honestly you’re missing out. Please don’t take that the wrong way – I still use & enjoy universal IEMs on a regular basis and find owning customs does not suddenly render UIEMs redundant.
However it’s important to understand although universals have become increasingly comfortable & effective at isolating noise, they are ALL still a significant notch down in both regards from CIEMs.
Let me just say this – that extra $100 ISN charge for a customs, along with a few hundred you’ll spend getting impressions of your ear canals made are quite possibly the BEST investment you can make in this hobby. Once you own your first set of customs you’ll immediately understand why!
CIEMs feel like there’s “nothing” sitting in your ears in a way even the best-fitting UIEM cannot, they block out significantly more background noise than you realised was getting through, and deliver a stronger feeling of immersing you in your own personal audio bubble. For noisy trips on planes & public transport they are simply unbeatable, but even in quiet environments they’re just far more satisfying to use.
Page 1 – Introduction, Packaging & Ergonomics
Page 2 – Sound Impressions & Technical Performance
Page 3 – IEM Comparisons
Page 4 – Cable Comparisons
Page 5 – Conclusion
try zisin a01-apopis you’ll be shocked (i’ve to say that i leave it in the freezer 24 hours to have the best results you can trust me or not) , c2 and h2 are among the worst cables i’ve listened to. Zisin and cayin ru7 and i can’t ask for more… can’t still find the same excitement with the sibling est 80 that have more forward voices but too shy highs, too thin or delicate.