The Munitio NINES score 4.5 out of 5 for build and 6.2 out of 10 for sound. That gap is not an accident or a manufacturing failure. It is structural, and it shows up again and again in earphones sold on their appearance.

This is not an argument that novelty earphones are bad. It is an argument that the thing you can see is almost never the thing you can hear, and that being clear about which one you are buying makes you happier with the purchase.

What people think determines the sound

Ask why a metal earphone should sound better than a plastic one and you will usually get some version of: metal is denser, denser is less resonant, less resonant is cleaner.

There is a grain of truth buried in that. A housing that rings audibly does colour the sound. But the leap from “metal doesn’t ring” to “metal sounds better” skips every part of the system that actually matters.

What actually determines the sound

Four things, roughly in order of importance:

1. The driver. Its size, its material, its motor, and how well it was manufactured. This is most of the answer. A good 9 mm dynamic driver in a plastic shell beats a poor one in machined copper every time, and it is the only component whose cost scales directly with sound quality.

2. The acoustic chamber behind the driver. The volume of air behind the diaphragm, and how it is vented and damped, sets the bass extension and the midrange balance. This is why two earphones using the identical driver can sound completely different. It is also the part most compromised by novelty design — when the housing has to look like a cartridge casing, the internal volume is whatever is left over after the styling.

3. The nozzle and filter. Bore diameter and any damping material in front of the driver shape the treble. A 5 mm nozzle with a mesh filter, as on the NINES, is a deliberate choice with audible consequences.

4. The seal in your ear. The single biggest variable, and the one entirely outside the manufacturer’s control. A poor seal costs you most of the bass, which is covered in the fit guide.

Housing material appears nowhere on that list except as a distant contributor to point two. It is a real factor and a small one.

Why novelty shapes tend toward the same sound

There is a pattern in earphones designed shape-first, and the NINES sit squarely inside it: heavy, warm, bass-forward, soft on top.

That is not a coincidence, and it is not laziness. It follows from the constraints:

• Odd shapes constrain internal volume, which tends to limit clean bass extension. The usual fix is to tune for a bass emphasis instead, which reads as “powerful” and hides the limitation.
• Heavy housings need a firm seal to stay put, so the stock tips are usually thick. Thick tips seal well, which reinforces the bass.
• A soft treble is safer. A shape-led product will be bought by people who are not primarily listening for detail, and a bright, revealing tuning is fatiguing and exposes bad source files. Rolling the top end off is the low-risk decision.

The result is a house sound that is genuinely pleasant, genuinely forgiving, and genuinely not detailed. The NINES review quotes it precisely: “obscenely smooth and non-fatiguing,” but with “sub-par clarity.”

The honest way to buy one

Ask yourself which of these two sentences is true:

“I want the best sound I can get for this money.”

If that is you, shape-led earphones are the wrong category. You are paying a machining premium that buys you nothing acoustically, and the tuning will be chosen to be safe rather than accurate.

“I want an object I enjoy owning, that also sounds pleasant.”

If that is you, they are a completely reasonable purchase, and you should judge them on the things they are actually good at: finish, durability of the housings, how they feel in the hand, and whether the tuning suits what you listen to.

Both are legitimate. The mistake is buying under the first sentence and being disappointed for reasons the product never promised to solve.

Three things worth checking before you buy any of them

Is the cable detachable? This decides the product’s lifespan more than anything else. Heavy housings put load on the cable joint every time they swing. A fixed cable means the first failure is terminal — the single hardest thing to defend about the NINES at $199.

What is the nozzle diameter? If it is unusual, third-party tips will not fit, and since stock tips harden over a few years you are relying on the manufacturer still existing.

What does the tuning do to your music? A warm, soft signature flatters compressed audio and dulls good recordings. If most of what you hear is streamed at 128 kbps or thereabouts, that is a feature. If you listen to well-mastered acoustic recordings, it is a cost.

None of those three questions is about metal.