Best cheap IEMs under $20, by sound

IEMs (in-ear monitors) are wired earphones that sit in your ear canal. Under $20, AliExpress sells some good ones, and the hard part is choosing by sound rather than by the spec sheet. These five are picked from published reviews, specifications and what owners say in community discussions. chi-fi has not tested them (see how we pick), and the prices are “from” prices, not live ones.

The short answer

• Most bass for the least money: the KZ Castor Bass, from $8.
• Clear, detailed mids in a metal shell: the KZ ZVX, from $8.
• Warm and easy to listen to for hours: the TANGZU Wan’er S.G, from $15.
• Warm, with more bass than the original Zero: the 7Hz x Crinacle Zero 2, from $15.
• Small, comfortable, with a nicer cable: the Moondrop CHU II, from $18.

If you want bass

The Castor Bass is built for it. Each earpiece has four small switches that change the bass and treble, giving 16 sound settings, and you flip them with the included pin tool. In the default setting the bass is big but mostly stays out of the way of vocals. Turn the bass switches up and it can spill into the mids and make voices muddy. There is no carry case, and the clear plastic can yellow over time.

The Zero 2 is the calmer way to get bass. Tuned together with the reviewer Crinacle, it is warm and bass-forward, which suits pop and hip-hop, and the treble stays smooth. The trade-off is little sparkle at the top and only average detail.

If you want a warm, relaxed sound

The Wan’er S.G has a warm, smooth sound that is easy to listen to for hours, and its light shells stay comfortable. It is not a pick for detail: technical performance is average, the sense of space is narrow, and the bass can blur into the mids a little. The stock cable tangles easily and has stiff ear hooks, so many owners replace it.

If you want detail

The ZVX is the one to look at. Reviewers like its clear, forward mids, good detail and tight, quick bass, and its all-metal shells feel solid for the price. Some reviewers find voices and instruments slightly unnatural, the metal makes it heavier and bulkier than most budget sets, and the box has foam ear tips only.

If you want comfort and a better cable

The CHU II has small metal shells that fit most ears, and a light detachable cable that is better than most at this price. The sound is fun, with good bass for the money. The mids sit slightly back, so guitars can sound thin, and the treble can feel bright if you are used to warmer earphones. Detail and separation are average.

What cheap costs you

At this price, expect average detail and a fairly narrow sense of space from most of these pairs. Extras are basic too: thin stock cables, and often no case. What you are choosing between is mainly tuning and comfort.

Before you buy

1. Check the cable connector. All five have detachable cables with a 2-pin connector. KZ lists 0.75 mm and 7Hz and Moondrop list 0.78 mm. The sizes are close, but check before you buy a replacement cable.
2. Plan to try other ear tips. Fit changes the sound more than anything else. The ZVX ships with foam tips only, and the Zero 2’s angular shells do not suit every ear. Ear tips are cheap.
3. They are easy to drive. The ZVX, Zero 2, Wan’er S.G and CHU II are listed at 18 to 32 Ω, which a phone handles without help. If your phone has no headphone jack, you need a USB-C dongle or adapter.
4. Read the listing options. On AliExpress, details like a microphone on the cable, colour and bundle are usually separate choices, so check them before you pay.

When to spend more

If you outgrow these, the Moondrop Kadenz is the step up in the catalog, from $197. It has strong, physical bass, swappable nozzles to change the treble, and a USB-C cable with a built-in DAC in the box. Reviewers rate it good rather than outstanding, and its heavy shell does not fit every ear.

The five picks below each list their own pros and cons.