I just finished writing my review on the Binary Acoustics EP321 MEMS in-ear monitor, when I noticed that there’s already $15 off the asking price, over at Amazon.
The EP321 only got released in December 2025, and it was great value for its asking price, so this is definitely a deal worth highlighting. There are cheaper options out there – check out my list of the best budget-friendly IEMs for that – but for this level of detail and engagement, it’s hard to beat under $300.
First discount on the EP321
MEMS hype, of MEMS the word?!
(Image credit: Future)
The EP321 has a MEMS driver, and that’s a bid deal. Unlike traditional dynamic drivers that use magnets and voice coils to move a diaphragm, a MEMS driver is etched onto a silicon wafer and moved by an electrical charge. That means the MEMS driver can start and stop vibrating almost instantly, resulting in a ‘fast’ sound and a high level of detail in the treble region.
To you and me, that means an airy treble that gives the whole sound a sense of detail, and engagement.
This is not just a boring treble-fest of clinical detail. As this has 6 drivers in it, there’s other more traditional drivers taking care of the meaty sub bass, and full, if slightly warm midrange.
For the pro or music lover, the EP321 is an engaging rather than laid back listen. Some listeners may perceive the higher frequencies as clinical or sterile, and if you prefer a warm, analog sound or natural midrange, it might not be for you.
But for those who value imaging (the ability to pinpoint the location of instruments in a mix) and loads of detail, the EP321 offers you performance that was impossible at this price point just two years ago.
Oh, and the build quality, featuring a 7.5g 3D-printed housing and stainless steel faceplates, is some of the best that I’ve seen in (and a bit above) the $300 range.