FiiO UTWS5 2025 review: IEMs with lossless Bluetooth?

The Fiio UTWS5 is a Bluetooth adapter that reminds me of the old fitness-focused earbuds. Instead of sounding old and dated, these headphones feature CD-quality sound with Bluetooth connectivity via aptX lossless technology, promising a superior audio experience. Does it deliver, and does the 2025 version fix previous issues with the original Fiio UTWS 5?

What I like about the Fiio UTWS5

The case features a nice metal top lid with rounded corners. It has a very soft look, and while it’s not exactly pocketable, I can still fit it in my pocket. That is assuming you’re alright with the bulge. Charging the predecessor from 2021 was a pain, as the metal contacts would fail to charge at times. This is all fixed on the new UTWS 5 version. The batteries use wireless charging instead. This ensures that the metal contacts are no longer required and will not corrode from sweat. Hopefully, this prevents them from getting battery issues in the future.

They are comfortable on my ears with the few IEMs I’ve tried them with. The smaller the better in this case, as you’ll be able to adjust it a little bit more. The weight of the earhooks on my ears doesn’t add much discomfort. The rubber hooks distribute the weight more evenly compared to a cable. The curvature of the hooks makes the adapter fit flush against the back of my ear. For fit, I found that they are comfortable to wear for more than four hours.

The main focus is that you’ll be able to get great sound with the support of many Bluetooth codecs. I tested them using aptX adaptive and LDAC, as these are the highest available Bluetooth codecs. Not many phones have Lossless aptX adaptive, so I have to use an adapter. In terms of how it affects the sound, they don’t sound too far off compared to going through a regular DAC-AMP combo. I’ve tried them with the Campfire Audio Satsuma and Sennheiser IE 600. Both of them sound pretty similar to when I connect them to a regular DAC AMP like the iFi Valkyrie. It’s more than enough that I wasn’t bothered while listening to music, walking, or on the train ride to work.

Does Bluetooth make it sound worse?

How does it sound when compared to a desktop DAC/AMP? Using the Fiio UTWS5 paired with the Sennheiser IE 600, there’s a slight lack in clarity, a touch shallower spatial depth, and a decrease in treble. The lack of clarity is subtle enough that I had to move back and forth between the UTWS5 and the iFi Valkyrie to tell. Listening to the track “Drone Corpse Aviator” by Archspire, I found it slightly harder to separate the instruments and vocals. The shallower spatial depth is noticeable in tracks like “Parachute” by Liel Bar-Z. All the tracks sound a little closer than I expected. While there is a slight decrease in treble, it’s mostly the upper treble that goes missing. The metal and brass instruments in the track “Get Movin” By Cut Papers sound a little quieter and a touch unnatural.

In the app, you get a bunch of features. There’s a 10-band EQ, Game mode for low latency, and an idle power mode to increase the battery life. The 10-band EQ is fully featured with advanced mode to adjust specific frequencies, Q-depth, Gain, and filter type. So if you really wanted to compensate for the decrease in treble, you can adjust it to your tastes in the app. I find that the latency was noticeable, but negligible without game mode turned on. Game mode ensures there’s little to no latency, resulting in better lip-sync during movies.

What I don’t like about the Fiio UTWS5

Of course, there’s no going around the fact that the case is huge. Either I put them in a cargo pant pocket or in a bag. The relatively short battery life doesn’t help either. In testing, the Fiio UTWS5 only lasts 3 hours and 16 minutes in our standard testing, less than half of the advertised 8 hours. This is fine during a commute to work, but it’s not great if you’re using it throughout the day. I found myself putting them back in the charging case often.

There are two versions of the Fiio UTWS5. This is only because you can choose between the MMCX and 2-pin versions. There aren’t any adaptors in the box, but you can get small third-party adaptors to swap from MMCX to 2-pin, and vice versa. It would have been nice if the hooks were interchangeable. Another option would be to shorten the earhook and include adapters for the MMCX connections.

Despite the features available through the Fiio Control app, it is slow and clunky to use. Switching between sections has a long loading screen that lasts at least five seconds. At least the options should be changed once and saved to the UTWS5 itself. However, there’s no way to change the EQ of the onboard microphones, which sound muffled.

UTWS5 2025 microphone sample:

Should you buy the Fiio UTWS5?

Unlike Fiio’s previous attempts at creating an IEM Bluetooth DAC, they have pretty much cracked the code. You get the CD-quality audio, with one compromise. The only problem is the short battery life, just enough for a commute but not enough to last a full day. I would recommend the Fiio  UTWS5 2025 edition for those who like a travel-friendly Bluetooth adapter for their IEMs. It could also bring new life to some of your older IEMs by giving you Bluetooth and EQ.

If you want to swap out IEMs frequently, you may want to consider 3.5mm Bluetooth DACs. There’s the Fiio BTR15, or the iFi Go BLU Air. Both of them are dongles that let you switch between different IEMs and even headphones. I would recommend those instead if you try out different IEMs. This is because both the MMCX and 2-pin connectors on the IEMs themselves wear out easily when compared to 3.5mm jacks.

Fiio UTWS5 review: FAQs