Custom IEMs
Universal IEMs
DAC & wireless
Accessories
ProShop & DIY
Start here
Comparison
Your earphone decides the connector, and none of the three changes the sound. 2-pin (two 0.78 mm pins) is the most common: 55% of the IEMs in our fit guide. It holds firmly and has a polarity to match. MMCX snaps on and turns, which suits over-the-ear wear. IPX is a smaller snap that also turns, used by Ultimate Ears customs, 64 Audio and, as T2, Westone. It doesn’t fit MMCX.
At a glance
| 2-pin (0.78 mm) | MMCX | IPX | |
|---|---|---|---|
| What it is | Two 0.78 mm pins that push into a socket | A round coaxial snap-on connector | A smaller round snap-on connector |
| Share of IEMs in our fit guide | 54.7% (plus 4.0% with 0.75 mm pins and 1.3% raised qdc/UE 2-pin) | 17.9% (plus 1.3% recessed MMCX) | 6.5% (IPX and T2) |
| Turns once fitted | No | Yes, unless the socket is keyed or recessed | Yes |
| Polarity to match | Yes: match the marked side | No | No |
| Variants | Flat or recessed socket; raised qdc/UE legacy; 0.75 mm (KZ, CCA) | Recessed (Sennheiser IE, AKG N40/N5005); Sony IER-Z1R | T2 sockets (Westone MACH, Pro X; UE 150–350) take our IPX plug |
| Typical brands | Moondrop, Truthear, Empire Ears, Vision Ears, AAW, 64 Audio universals | Shure, Campfire Audio, FiiO, final, Dunu; Sennheiser IE (recessed) | Ultimate Ears Pro customs, 64 Audio, Westone (T2) |
| Fits the others? | No | No: MMCX and IPX are different sizes | No |
| Connector change on a Null Audio cable | USD 50 per cable, plus any price difference for the new plug | ||
Share of the 448 IEMs with a detachable cable in our fit guide, October 2026.
In use
Durability
From the 2-pin cables and sockets we see for repair. Cheap pins cause most of the trouble.
What goes wrong: low-quality pins are machined to loose tolerances and can come out at 0.80 mm instead of 0.78 mm. An oversized pin stretches and damages the earphone’s socket. Some brands make their pins oversize on purpose, so the cable feels snug and fewer come back under warranty.
How we build ours: our pins are machined to 0.78 mm ±0.005 mm, so they hold firmly without forcing the socket open.
Null AudioNull AudioWhat goes wrong: every time a cable goes in and out, the socket wears a little, and after many swaps the plug can feel loose. This is why some makers oversize their pins: to hide a socket that has already loosened.
How we build ours: a true-size pin doesn’t widen the socket further. Swap cables only when you need to, and pull the plug straight out.
Already loose? Our sister brand AAW can reshell your IEMs and change the socket system to AAW’s own 2-pin socket. A spring hook inside it latches onto the pins, so it doesn’t loosen, and it’s matched to Null Audio pins.
Null AudioNull Audio and AAWWhat goes wrong: the plastic body around the pins ages, turns brittle and cracks, and the pins can work loose.
How we build ours: our 2-pin housings are made from a high-quality PP (polypropylene) compound, chosen so they don’t crack with age.
Null AudioNull AudioWhat goes wrong: cheap pins carry only a thin flash of gold. Once it wears through, the base metal underneath oxidises, and the contact suffers.
How we build ours: our pins carry genuine 24k gold plating, made to last rather than a thin flash.
Null AudioNull AudioDurability
What goes wrong: an MMCX plug turns freely in its socket, and every turn rubs the contacts, so the gold plating wears faster than on a connector that can’t turn.
How we build ours: our MMCX plugs are made to a tighter tolerance, with a more rigid snap ring, so they turn with more resistance and the contacts wear less.
To make it last: let the plug turn when it needs to, but don’t spin the earphone on the cable.
Null AudioNull AudioWhat goes wrong: the signal runs through one tiny male pin into a female socket that is usually made of two halves. On a badly made socket with loose tolerances, the pin can go in at a slight angle and either bend, or lever the two halves apart. The result is a loose contact or a complete break.
How we build ours: inside our MMCX connectors, a white plastic block surrounds the female contact. It holds the contact firmly in place and guides the pin in straight, so fewer pins bend and fewer sockets break.
To make it last: line the plug up and push it straight in; pull it straight out, holding the plug.
Null AudioNull Audio
What goes wrong: the IPX plug is metal, but the socket sits in a softer plastic base. Sideways force on the plug, such as a tug on the cable or a knock, can occasionally damage the socket.
To make it last: keep sideways load off the plug: let the cable hang or run over the ear without pulling to the side, and unplug straight out.
Null AudioNull Audio repair experience
Unplug by holding the plug, never by pulling the cable; keep plugs and sockets dry and away from sweat and cleaning chemicals.
Null AudioNull Audio support centreOur customers
Share of connector choices on Null Audio cable orders over the last 24 months. Percentages only.
51.7%
Null AudioNull Audio orders, Oct 2024 – Oct 202613.1%
Null AudioNull Audio orders, Oct 2024 – Oct 202613.1%
Null AudioNull Audio orders, Oct 2024 – Oct 202610.6%
Null AudioNull Audio orders, Oct 2024 – Oct 202611.5%
Null AudioNull Audio orders, Oct 2024 – Oct 2026Before you order
Variants
Our Standard 2-pin (0.78 mm) fits both. Flat 2-pin is for flat sockets only.
Null AudioNull AudioKZ C-pin 0.75 2PIN for raised sockets, KZ / 64 Audio 0.75 Flat 2PIN for flat ones. See the KZ guide.
Null AudioNull AudioUE/UM/QDC 2PIN Legacy
Null AudioNull AudioSennheiser IE 200–900 and AKG N40/N5005: IE300/600/900. See the Sennheiser IE guide.
Null AudioNull AudioWestone MACH and Pro X, UE 150–350: our IPX plug fits.
Null AudioNull AudioCustom IEMs
Every AAW custom uses AAW’s own recessed 0.78 mm 2-pin socket. A spring hook inside latches onto the pins, so the socket doesn’t loosen with use, and it’s matched to Null Audio pins.
Null AudioNull Audio and AAWAvailable free on request, but MMCX sockets and connectors aren’t covered by the warranty, and an MMCX repair costs USD 100.
Null AudioNull Audio support centreBuilt with either an IPX or a 2-pin socket: choose IPX or Flat 2-pin (0.78 mm) to match.
Null AudioNull AudioChanging connector
USD 50 per Null Audio cable, plus any price difference for the new plug or pins and shipping both ways.
Null AudioNull Audio support centreOur interchangeable system changes the earphone-side connector on one cable. Current tips: 2-pin, IE300, A2DC, IPX, Pentaconn Ear and qdc 2-pin.
Null Audio configuratorNull Audio cable pagesGuides
Questions
None of them. The connector carries the signal; the sound comes from the earphone and the cable’s conductors.
No. The socket is part of the earphone, so choose the cable connector that matches it. We build every cable with the connector you choose.
No. They look alike but are different sizes and don’t fit each other.
No. KZ and CCA use 0.75 mm pins: see the KZ guide.
Each wears in its own way: see What wears above. Unplugging by the plug, not the cable, matters more than the connector type.
Keep reading
Sources
Join the Null Audio list for first word on new cables and early previews of each collection. As a welcome, here’s USD 5 off your first order, and shipping is free worldwide.
Thank you for joining us. Here is your USD 5 welcome coupon. Enter it at checkout, or apply it to your order now.
