Choose a 4.4 mm balanced cable if your player or dongle has a 4.4 mm output; it is the common balanced standard on current portable gear. If your only balanced output is 2.5 mm, choose 2.5 mm. If you only have a 3.5 mm jack, choose 3.5 mm. A balanced plug won't work in a single-ended 3.5 mm jack, so the plug has to match the socket.
This guide is for anyone ordering an IEM or headphone cable who isn't sure which player plug to pick. You'll learn what 4.4 mm balanced output actually changes, how it compares with 2.5 mm and 3.5 mm, and how to check what your own device supports.
Key takeaways
- A 3.5 mm single-ended plug has 3 contacts, a 2.5 mm balanced plug has 4, and a 4.4 mm balanced plug has 5.
- Japan's JEITA added the 4.4 mm five-pole balanced plug to standard RC-8141C in 2016.
- The FiiO KA13 dongle is rated at 170 mW from 3.5 mm and 550 mW from 4.4 mm, both into 32 Ω.
- Balanced output roughly doubles the available voltage swing, but sensitive IEMs rarely need the extra power.
- Ethos Ultra comes with 3.5 mm, 4.4 mm balanced and USB-C DAC plugs in the box.
3.5 mm, 2.5 mm and 4.4 mm plugs at a glance
A player plug is the end of the cable that goes into your phone, player, dongle or amplifier. It is separate from the connector on the earphone end. The table shows the plugs you'll meet most often.
| Plug | Type | Contacts | Where you'll find it |
|---|---|---|---|
| 3.5 mm | Single-ended | 3 (left, right, shared ground) | Almost every player, laptop, dongle and older phone |
| 2.5 mm | Balanced | 4 | Some portable players, especially older Astell&Kern and other DAPs |
| 4.4 mm (Pentaconn) | Balanced | 5 (four signal contacts plus a ground/shield) | Most current mid- and high-end players and many dongle DACs |
| 4-pin XLR | Balanced | 4 | Desktop amplifiers |
| 6.35 mm (1/4") | Single-ended | 3 | Home amplifiers and studio gear |
Desktop plugs: 4-pin XLR and 6.35 mm
At home, you may meet two more plugs. The 4-pin XLR is a balanced plug with 4 contacts, used on desktop amplifiers. Some amplifiers use a pair of 3-pin XLR plugs instead, one per channel. The 6.35 mm plug is the single-ended jack on home amplifiers and studio gear.
The contact count tells you what a plug can carry. Three contacts means left, right and a shared ground. Four or more means each channel can have its own return, which is what makes a connection balanced.
What does 4.4 mm balanced actually mean?
A single-ended connection is one where the left and right channels share one ground wire back to the amplifier. A balanced connection is one where each channel has its own return wire. The amplifier then drives each earpiece with two amplifier sections pushing in opposite directions.
The 4.4 mm plug is the most common way to carry that connection on portable gear. Its pin order is L+, L−, R+, R− and ground. That order is set in Japan's JEITA standard RC-8141C, which added the five-pole plug in 2016 (Phile-web). Pentaconn is the brand name of Nippon DICS, the company behind the connector, which is why you'll see “Pentaconn” on many 4.4 mm jacks.
Why a shared ground matters
With a shared ground, a little of each channel's signal can leak into the other through the common wire. Separate returns remove that path, which can improve channel separation. The effect depends on the device and the cable, so treat it as a possible benefit rather than a promise.
Does balanced output give you more power?
Usually, yes. Driving each side from both ends roughly doubles the available voltage swing. Many players and dongles therefore deliver noticeably more power from their balanced output. Manufacturers' own figures show how large the difference can be:
| Device | 3.5 mm single-ended | Balanced |
|---|---|---|
| FiiO KA13 dongle | 170 mW into 32 Ω | 550 mW into 32 Ω (4.4 mm) |
| Moondrop Dawn Pro dongle | 2 Vrms | 4 Vrms (4.4 mm) |
| iBasso DC04 Pro dongle | 2 Vrms | 3 Vrms |
| Astell&Kern AK240 player (2014) | 2.1 V | 2.3 V (2.5 mm) |
Sources: FiiO KA13 and Moondrop Dawn Pro specifications, and Stereophile's AK240 review.
The AK240 shows that the gap is not always large. Its balanced output was only 0.2 V higher than its single-ended one. Whether you'll hear a difference depends on the device. Some players have a better-engineered balanced stage than single-ended; others are close to identical.
Should you choose 2.5 mm or 4.4 mm balanced?
If your device has both, choose 4.4 mm. It is larger and sturdier than 2.5 mm and has a dedicated ground contact. It is also a published standard, and it has become the common balanced connector on portable gear.
The 2.5 mm balanced plug is a four-contact TRRS plug. It came first: the Astell&Kern AK240 had a 2.5 mm balanced output in 2014. It is still a good choice if it's the only balanced output you have. Its thinner barrel is the main reason we suggest 4.4 mm when you have the option.
Can you adapt between plugs?
You can adapt a balanced cable to another balanced plug, for example 4.4 mm to 2.5 mm, with a short adapter. You can also use a 4.4 mm cable in a 3.5 mm jack, but only with an adapter designed to convert balanced to single-ended. That adapter shares the ground again, so you lose the balanced benefits.
You can't plug a balanced cable straight into a 3.5 mm jack. If you use several devices, a cable with an interchangeable player end avoids adapters altogether. Ethos Ultra starts at USD 89 and comes with 3.5 mm, 4.4 mm and USB-C plugs in the box.
What about phones and USB-C?
If your phone has no headphone jack, you need an adapter, a dongle or a DAC cable. Apple's USB-C to 3.5 mm adapter is 3.5 mm only, so it has no balanced output. Reference Audio Analyzer measured the EU model A2155 at about 0.5 Vrms maximum, with 0.3 Ω output impedance (Reference Audio Analyzer).
If you want balanced output from a phone, use a dongle DAC with a 4.4 mm socket. Or choose a cable with a built-in DAC: we offer USB-C DAC plugs with ALC5686 or ESS9280C chips, and Lightning plugs for older iPhones.
Which one fits depends on your iPhone. Apple moved to USB-C with the iPhone 15; the iPhone 5 to iPhone 14 use Lightning (Apple). Capri is our Lightning DAC cable with direct balanced output. It is rated at up to 128 mW into 16 Ohms, with output impedance under 1.0 Ohms.
Which plugs can you order?
Every Null Audio cable is built to order with the player plug you choose: 3.5 mm (straight, L-shape or balanced), 2.5 mm, 4.4 mm, 4-pin XLR, a pair of 3-pin XLR, and USB-C or Lightning DAC plugs for phones. Here is how to pick:
- Look up your player or dongle in our player plug guide to see which outputs it has.
- Check your earphone's connector in our IEM cable connector guide, or look your IEM up in Find My Cable.
- Choose a cable from IEM and headphone cables or, for full-size headphones, headphone cables.
Not sure which output your device has? Tell us your player and earphones, and we'll recommend the right plug. Every cable has a 1-year warranty.
Frequently asked questions
Can I plug a 4.4 mm balanced cable into a 3.5 mm jack?
Not directly. You need an adapter designed to convert balanced to single-ended, which shares the ground again, so the balanced benefits are lost. A cable with an interchangeable player end, such as Ethos Ultra, avoids the adapter.
Is 4.4 mm better than 2.5 mm balanced?
Both carry a balanced signal. The 4.4 mm plug is larger and sturdier, has a dedicated ground contact, and is a published JEITA standard. Choose 2.5 mm only if it is the only balanced output your device has.
Does a balanced cable improve sound quality?
A balanced connection gives each channel its own return wire, which removes the shared-ground path between channels. Many players also deliver more voltage and power from their balanced output. Whether you hear a difference depends on the device and your earphones.
How much more power does a 4.4 mm output give?
It depends on the device. FiiO rates the KA13 dongle at 170 mW from 3.5 mm and 550 mW from 4.4 mm into 32 ohms. Moondrop rates the Dawn Pro at 2 Vrms single-ended and 4 Vrms balanced.
Do sensitive IEMs need a balanced output?
No. Sensitive IEMs rarely need the extra power, and more output can even raise background hiss. Balanced is a benefit, not a requirement.
What is a Pentaconn plug?
Pentaconn is the brand name of Nippon DICS, the company behind the 4.4 mm balanced connector. The 4.4 mm five-pole plug was added to Japan's JEITA standard RC-8141C in 2016, with the pin order L+, L-, R+, R- and ground.
Sources
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