Sennheiser just refreshed two of its most popular wired models—the CX 80S and HD 400S—by swapping the old 3.5mm plug for a USB‑C connector. The new CX 80U ($39.95) and HD 400U ($99.95) are built for a world where phones, tablets, and laptops increasingly lack a headphone jack. But instead of a cheap dongle, Sennheiser built the DAC and amp right into the cable.

Here’s what that means for everyday listening.

What’s New: USB‑C with Built‑in Hi‑Res DAC

Both models now terminate in a USB‑C connector. Inside that connector (or inline housing) is a digital‑to‑analog converter that supports 24‑bit / 96 kHz playback. That’s proper hi‑res—higher than CD quality (16‑bit/44.1 kHz). Plug them into any USB‑C device—iPhone 15/16. iPad, Android phone, Nintendo Switch, Steam Deck, MacBook, or Windows laptop—and the headphones show up as a standard audio device. No drivers, no extra battery, no Bluetooth pairing.

The signal path stays digital until the last possible moment, which means lower latency than any wireless solution and zero compression. What you hear is exactly what the source sends.

Sennheiser HD 400U: Over‑Ear Comfort with Passive Isolation

The HD 400U inherits the HD 400S’s closed‑back, on‑ear (actually over‑ear for smaller to medium ears) design. It’s lightweight, foldable, and comes with a carrying pouch and a detachable USB‑C cable. The cable is fixed to the left ear cup—no swapping for a 3.5mm, but the detachable design means you can replace it if it wears out.

Sound signature: Strong, punchy bass without bleeding into the mids. The HD 400 series has always leaned a little warm and energetic, and the 400U follows that tradition. Vocals are clear, and the closed back provides excellent passive noise isolation—about 15‑20dB of attenuation. That’s enough to cut office chatter or bus engine rumble without needing active electronics.

Comfort: The headband padding is decent, and the ear cushions are soft leatherette. Clamping force is moderate. They’re fine for a few hours, but larger ears might feel cramped after a long session. At 99 bucks, build quality is what you’d expect—mostly plastic, but it feels durable enough for daily commutes.

Sennheiser CX 80U: Lightweight In‑Ears for On‑the‑Go

The CX 80U replaces the CX 80S. Same compact, angled nozzle design that sits flush in your ear. Three sizes of silicone tips are included. The housing is plastic and very light—you’ll forget you’re wearing them.

Sound: Balanced with a slight bass lift. Not as aggressive as the HD 400U. The CX 80U aims for a more neutral, all‑rounder tuning. Mids are present, highs are smooth (no piercing peaks), and bass has decent extension for a $40 earphone. It won’t satisfy bass heads, but for podcasts, calls, and most music genres, it’s clean and non‑fatiguing.

The cable has an inline MEMS microphone and a single button for play/pause and call control. No volume rocker, which is a minor annoyance. But the mic quality is surprisingly good—MEMS mics are small, low‑noise, and capture full‑range audio much better than old electret capsules.

Both Share the Same Core Upgrade

The real story here is the USB‑C digital audio path. Compared to the old 3.5mm versions, the U‑series benefits from:

Higher resolution: 24‑bit/96kHz vs. whatever your phone’s internal DAC outputs (often 16‑bit/48kHz).

Lower noise floor: The digital connection avoids the analog interference you sometimes get from a phone’s headphone jack.

Universal compatibility: Works with everything USB‑C, including devices without analog audio output.

No battery required: Unlike Bluetooth headphones, these never need charging.

The downside? You can’t use them with older devices that only have a 3.5mm jack unless you use a USB‑C to 3.5mm adapter (which defeats the purpose). And the cable is now less replaceable than a standard 3.5mm cable—though Sennheiser does sell replacements.

Who Should Buy?

CX 80U ($39.95): Perfect for students, commuters, or anyone who wants a cheap, reliable wired earphone for their USB‑C phone. Great for Zoom calls thanks to the MEMS mic.

HD 400U ($99.95): Good for office workers, gamers, or travelers who want better passive isolation and a more fun, bass‑forward sound. The detachable cable and carrying pouch add value.

Both are straightforward, no‑nonsense upgrades. Sennheiser didn’t reinvent the wheel—they just gave two solid budget wired models a modern connector. And for the price, the sound quality punches exactly where you’d expect from a company that’s been doing this for 80 years.

Bottom line: If you’ve already gone all‑in on USB‑C devices and you’re tired of dongles, the CX 80U and HD 400U are smart, affordable fixes. Just don’t expect wireless convenience or active noise cancellation. These are wired, passive, and proud of it.

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