The Xiaomi Mi In-Ear Headphones HD. Business Insider/Jeff Dunn

Despite the tech world's sudden aversion to headphone jacks, traditional 3.5mm headphones are still the best source of value. Bluetooth and USB-C will eventually be the norm, but for now, taking the jack away mostly gives audio companies a way to drive more revenue. It also gives them less incentive to build those affordable diamonds in the rough.

I was reminded of this after spending a few weeks with the latest in-ear headphones from Chinese tech firm Xiaomi, the Mi In-Ear Headphones Pro HD. They’ve got a terrible name, and they only work with the old headphone jack. But in both sound and design, they are way better than their $40 price tag suggests.

Though Xiaomi is best known for making smartphones, it’s built a bit of a reputation for producing these sort of quality earphones on the cheap. Its “Piston” line is well-known among cheapie audiophiles, and its Mi Hybrid earphones were a nice little travel pair for bass lovers.

Like all of those predecessors, the Mi Pro HD neither looks nor feels like it costs less than $40. They’ve got this silver, aluminum finish that’s handsome, but not showy. There’s a handy three-button remote for taking calls, pausing and skipping tracks, and changing volume, though the skipping and volume features only seem to work on Android. And while I can’t guarantee the longevity of any pair of budget headphones, the rubbery cable here has shown no signs of fraying in the two months I’ve spent taking it in and out of my pockets.

It’s all very comfortable, too. Though the Mi Pro HD are made of metal, they don’t drag on the ears. The speakers themselves are angled, so they slide in and stay in without much effort. To put it anecdotally, the low weight and soft rubber tips allowed me to wear them for a whole five-hour flight without issue.

The downside is that they don’t block out much external noise. It’s not the worst if you play things at a louder volume, but in a noisy environment, bits of the outside world will creep their way in. They’re not sweatproof, either, so don’t expect to take them running.

Plus, these being in-ear headphones, there’s always a chance that the fit might not jive with you as easily as they did with me. Xiaomi puts four different-sized eartips in the box, which is great, but some people may have to tinker to find a sound and fit they enjoy.

Whatever the case, that sound is very good. It’s a mildly “bright” signature, so the upper midrange and lower treble are usually pushed a little more than usual. That means things like guitar leads, cymbal crashes, and vocals are most prominent, but they stay clear and energetic throughout. There’s a surprising amount of width to it, too, so you can separate the different parts of a song. I find it particularly fun with rock — a punk track like PUP’s “DVP” just explodes, but the instrumentation doesn’t bleed into itself.

All that said, there’s usually enough low-end if a song calls for it. When the bass blasts through the door on Run the Jewels’ “Hey Kids,” it’s not earth-shattering, but it still hits you. While this may be a no-go for Beats-loving bassheads, it’s not sloppy, and it’s not so weak as to make the whole sound unbalanced.

They still cost $40, though, so there are blemishes. The earphones themselves are actually built by another firm, 1More, whose Triple Driver in-ears are a similarly excellent value. Compared to those, the Mi Pro HD don’t have the same level of depth or sharpness. They also get harsh if you crank the volume to the max, as “ess” sounds get too piercing for comfort. This is when that poor sound isolation becomes a problem.

The Triple Driver headphones cost $100, though. For less than half of that, the Mi Pro HD are at least comparable in terms of clarity, crispness, and comfort.

There’s a question of whether or not you should buy any 3.5mm headphone in an increasingly dongle-infested world, and these may not be the absolute best you can buy for $40, but value like this just doesn’t exist with Lightning, USB-C, or Bluetooth pairs yet. All of those have some extra cost attached today — Apple's licensing fees drive up Lightning pairs slightly, the USB-C market is nascent, and good wireless tech is still sold at a premium.

3.5mm headphones may be fading away, but they're a commodity. As such, they make it easier to find value for money. The Mi Pro HD are a late reminder of that. If you’re looking to upgrade your basic earbuds, or you need a secondary pair for the road, give them a look.