Wireless or Wired: Sennheiser IE 100 Pro Wireless Earphones for Professional Creators Review

＜IE 100 PEO Wireless＞

The IE 100 PRO BT BUNDLE is a professional in-ear monitor from SENNHEISER that was released as a limited edition and it has received high praise. Many people considered purchasing it due to its reputation, but it sold out incredibly fast. Now, the newly released IE 100 PRO Wireless is essentially the same model as the IE 100 PRO BT BUNDLE. It is a set product that combines the professional-grade in-ear monitors IE 100 PRO with the Bluetooth adapter IE PRO BT Connector.

While the IE 100 PRO Wireless is not exactly the same as the IE 100 PRO BT BUNDLE, the two are very similar. In this review, we will evaluate the IE 100 PRO Wireless Red and highlight the differences between the two.
※Please note that since this product is a variation with the same components, this review includes some content and shared reviews of the IE 100 PRO BT BUNDLE and the IE 100 PRO.

Wired Cable Included! Usable Both Wirelessly and Wired

＜Included Wired and Wireless Kit＞

When you open the package, you'll find the IE 100 PRO in its wireless configuration. Although the product name is IE 100 PRO Wireless, a wired cable is also included to allow you to use the earphones in either wireless or wired mode.

The only differences between the IE 100 PRO BT BUNDLE and the IE 100 PRO Wireless are:
・The packaging
・Availability of color variations
That's it—just those two points.

＜Enable Bluetooth from iPhone Settings to Pair＞

We started by checking the Bluetooth connection.

Press and hold the [•] button on the remote for 3 seconds, and you'll hear "Power on" in English from the earphones, indicating that they are powered on. With the earphones in this state, turn on Bluetooth on your device.

Select “IE PRO BT Module” to connect (pair), and setup is complete. Once you play music on your device, you can listen via Bluetooth.

The sound quality check yielded very favorable results. Of course, further evaluation with other monitoring equipment is necessary, but basic aspects such as “bass output” and “instrument balance” can be reliably assessed even over Bluetooth. For example, it’s possible to distinguish between uncompressed WAV files and compressed MP3 files. Even when watching YouTube, I could tell the difference between videos with good and poor audio quality.

Additionally, the IE 100 PRO Wireless supports the Bluetooth profile A2DP and codecs including SBC, AAC, AptX, and AptX Low Latency. Thanks to the high-quality AAC and AptX codecs support, you can use it with confidence.

＜Comes with Replacement Eartips and a Carrying Pouch＞

In addition to the main unit, wired and wireless adapters, the package also includes a pouch, replacement eartips, a cleaning tool, and a charging cable for the IE PRO BT Connector. The IE PRO BT Connector charges via a USB-C port.

Next, I switched to the wired cable to check the audio quality in wired mode.

Powerful Bass That Defies Its Looks

The IE 100 PRO boasts a wide frequency response range of 20Hz to 18kHz. While this is an impressive spec on paper, the real question is how well it performs in practice, given its compact size. I immediately tested it with various reference tracks, and the most surprising result was just how much bass it produces.

This isn't an exaggeration — the unit delivers a solid, stable low-end that qualifies as monitor-grade quality, all from such a small device. Beyond just bass guitar, it accurately reproduces the body resonance of a kick drum in the 50–80Hz range, as well as the deep lows of EDM-style kick drums and synth basses that all have remarkable resolution.

Unlike consumer-grade models that often exaggerate the bass, the IE 100 PRO offers tight, well-balanced low-end for bass-heavy genres like EDM and dance music, while delivering natural lows for classical music.

To be honest, I didn’t expect much low-end from such a compact unit, but it completely exceeded my expectations. In fact, it may allow for more precise monitoring than some speaker setups and could be used similarly to over-ear headphones.

＜Deep Bass That Defies the Small Appearance＞

The excellent bass performance is likely influenced by the high level of sound isolation. The earphones have a complex internal structure that reveals meticulous hardware design, and when worn, they fit like custom in-ear monitors made just for you.

Powerful Sound That Feels Close to Your Ears

As I mentioned earlier, the low-end performance is impressive, but the IE 100 PRO also delivers strong performance across the rest of the frequency spectrum. A defining feature of its sound is how close and intimate it is. It feels as if the sound is playing inside your head. Compared to over-ear headphones, the sound image is even closer, centered right around the middle of your head. This could be a significant advantage in loud environments like on-stage monitoring.

The transition from mid to high frequencies is smooth and detailed. The highs come across as slightly energetic, but this is expected to mellow with some use as the components break in (a process often referred to as "burn-in" or aging). This seamless frequency response is likely thanks to the continued use of the 10mm dynamic transducer, which is also featured in the IE 40 model.

＜A Skeleton Design That Reflects Confidence＞

There was once a boom in In-ear monitors balanced armature drivers, but one of their weaknesses is that they often require multiple drivers to cover a wide frequency range, which can result in unnatural transitions due to crossover points. The IE 100 PRO, on the other hand, uses a compact dynamic driver, meaning it covers the entire frequency range with a single unit. This eliminates phase differences and crossover inconsistencies. As a result, the sound has a coherent, unified quality that is immediately noticeable when listening.

Now that we've introduced the IE 100 PRO Wireless, what do you think? This product seems especially suitable for those who find that traditional audio-focused earphones overly color the sound and don't suit their ears. Although some may initially be hesitant about switching to wireless, once you try it, it's hard to go back. Use it wirelessly while on the move, and switch to wired mode when you arrive at the venue. The IE 100 PRO Wireless can be considered to be a professional-grade wireless earphone that adapts to a variety of situations.

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