FiiO BTR3K – Review



| Bluetooth Amp | USB DAC | Bluetooth 5.0 |

🎧 We are reviewing the FiiO BTR3K, the 2nd generation of the BTR3 Bluetooth amp series.

The BTR3K is part of the latest generation of Bluetooth adapters from FiiO, like the FiiO BTR5, and released after the:

Likewise many of the recent Bluetooth-enabled products from FiiO, the FiiO BTR3K carries a Hi-Res Audio Wireless certification.

In addition to this, the FiiO BTR3K features a Qualcomm CSR8675 Bluetooth chip with a modern BT 5.0 version that offers A2DP, AVRCP, HFP, HSP profiles and supports lossless wireless codecs.

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FiiO BTR3K Review

Tests & Scores


Advanced Features

The FiiO BTR3K features include advanced options such as:

  • Dual simultaneous connection
  • CTIA controls compatibility
  • Noise cancelling microphone for phone calls
  • Codecs light indicator



FiiO BTR3K weight in Ounces and FiiO BTR3K weight in grams.

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Accessories & Packaging

The FiiO BTR3K comes packed inside a medium-sized, white box with a clean design – similar to many other products from the brand.

The unit is placed inside, surrounded by a protective, cushiony piece that is 3 times larger than the device itself – worry-free protection.

Bundled with the device, users will find an USB cable and a plastic clip.

gramophone-25660 3.75/5



The FiiO BTR3K has a stylish look, with an all-dark design that is packed in a seamless metal shell with both frontal and rear glass panels.

To smooth out the form factor, the BTR3K has rounded ends on all 4 edges and concave ends that are far from showing any sharp parts – resulting in a very comfortable and natural grip.

As you might noticed, the FiiO BTR3K has the same name as the previous BTR3 model, with the addition of a “K” at the end of the name. The generational proximity with the BTR3 extends, also, to aesthetics and design; in fact, both the BTR3 and BTR3K will look identical at first sight.

Nonetheless, the FiiO BTR3K has a significant redesign over it’s clip section, where the BTR3 was fixed and now the newer BTR3K offers the clip section as a detachable addon that comes bundled with the unit. This design decision allows the BTR3K to reach a much thinner profile when the clip is detached and, yet, not loosing it’s clip functionality.

The FiiO BTR3K is a small Bluetooth amp, that falls within FiiO’s standards in size, measuring 58mm x 25mm x 12mm and weighting about 23 grams.

gramophone-25660 4.75/5



Operation & Control

The BTR3K has 4 buttons on it’s right edge, these will allow the full control of the device without any complex multibutton combinations.

Each button has a different and unique shape and size, which will allow users to recognize the buttons functions by simple touch without necessarily having to look at them – this might seem as a trivial fact, yet on daily use and while having the adapter inside a pocket, this feature will be a very welcomed design detail that will ease-up the it’s usage.

An additional tech incorporation of the FiiO BTR3K is it’s compatibility with CTIA controls, this enables the use of the CTIA playback controls of your headphone’s cable.

The main functions of the buttons are:

Power Button:

  • Press and hold: Power on/off
  • 2x click: switch between devices

2nd Button:

  • A single press: Play, Pause music or Answer/End calls
  • 2x click: Activate Siri

Volume UP Button:

  • A single press: Volume up
  • Press and hold: Previous song

Volume Down Button:

  • A single press: Volume down
  • Press and hold: Next song

LED Status Light: The front glass of the FiiO BTR3K, actually, hides a “FiiO” logo that will illuminate and change color according to the Bluetooth codec being used – it will also serve as a status indicator.

The colors corresponding to each codec are:

  • blue (SBC)
  • cyan (AAC)
  • white (LDAC/DAC)
  • green (LHDC)
  • purple (aptX/aptX low latency)
  • yellow (aptX HD)

gramophone-25660 4/5

FiiO BTR3K buttons
FiiO BTR3K buttons


Battery Life

Inside this tiny device there is a rechargeable lithium battery with a capacity of 330mAh.

The FiiO BTR3K can provide as much as 11 hours of continuous playback and can be fully recharged in less than 90 minutes through it’s USB Type-C connector, when using a compatible charger that outputs 5V 0.5A (for example, standard USB 2.0 port from a computer)

The battery runtime of the BTR3K is inline with the recent Bluetooth adapters of the brand and is, even, nearly 25% more than on the FiiO BTR5.

gramophone-25660 3.5/5

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FiiO BTR3K charging port
FiiO BTR3K charging port


Construction & Build

If you are an owner of recent FiiO products, you should expect the same level of heavy-duty build with the FiiO BTR3K.

The main shell is fully made of aluminum alloy while the front and back are 2.5D reinforced glass.

The quality materials used for it’s build can be felt when holding it on the hands, the device will inspire confidence to use it without fear of falling apart.

As we have mentioned before, the BTR3K comes with a clip addon; this clip accessory is made of transparent plastic. This will not provide the same metal build as on the older FiiO BTR3 but does neither feel cheap nor too fragile.

gramophone-25660 5/5

FiiO BTR3K with clip
FiiO BTR3K with clip


Formats Compatibility

The FiiO BTR3K is equipped with dual AK4377A DAC chips and a Qualcomm CSR8675 that supports lossless Bluetooth codecs.

Fortunately, this Bluetooth amp will allow audio-enthusiasts to benefit and enjoy lossless and low-latency sound that can be switched at will and on-the-fly.

The codecs supported are :

  • AAC
  • SBC
  • aptX Low Latency
  • aptX HD
  • LDAC
  • LHDC

gramophone-25660 5/5

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All the ports and connectors of the BTR3K are distributed through out the top and bottom edges. The top edge holds an USB Type-C connector that is used as a charging port and as the connection for USB DAC functionality; while the bottom edge is the area where both the 3.5mm single-ended headphone connector and the 2.5mm balanced headphone connector reside.

Thanks to it’s newer Bluetooth 5.0 and chip backed up by Qualcomm, the FiiO BTR3K showed a stable Bluetooth connection without any frequent dropouts of signal.

gramophone-25660 4.25/5

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Seeing such a small and affordable BT adapter/amp that bundles DAC capabilities, users might be unsure of the usability and quality as a dedicated DAC.

When our team measured the FiiO BTR3K, we were greeted with a remarkably flat frequency response that was equally as flat in Bluetooth mode and USB DAC mode – making this BT amp, also, a ridiculously tiny external USB DAC that can offer excellent performance.

When paired with in-ear monitors and full-sized headphones, the BTR3K showed no significant variation on it’s sound outputted, conserving the true original sound signature and small audio personality details of each headphone.

One of the most remarkable upgrades on the FiiO BTR3K is the dual headphone connector with the addition of a balanced 2.5mm with a huge bump in power output. This newly added balanced headphone connector brings to the table a 300% power output boosting that can reach up to 78mW (32Ω), which proved to be more than enough to drive most popular earphones on the market and was even to couple up with many full-sized headphones with sufficient volume margin.

Thanks to it’s CSR8675 chip, dual independent crystal oscillators and supported by a two high-performance AK4377A DAC chips, the FiiO BTR3K can grant 24-bit transmission and lossless wireless audio codecs that can adapt to any audiophile’s needs.

Among the technical specifications directly related to audio that might interest audiophiles, the FiiO BTR3K offers a SNR of 122dB with 118dB of crosstalk and a noise floor of 2uV.

gramophone-25660 5/5

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Frequency Response (raw)

FiiO BTR3K Frequency Response Curve

FiiO BTR3K frequency response curve
FiiO BTR3K frequency response curve

FiiO BTR3K Frequency Response Curve – DAC vs Bluetooth

FiiO BTR3K DAC and Bluetooth frequency response curve
FiiO BTR3K DAC and Bluetooth frequency response curve

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FiiO BTR3K Technical Specifications

TypeBT adapter/USB DAC
Music PlayerNo
Battery11 hours
FormatsSBS, AAC, aptX, aptX-LL, aptX-HD, LDAC
Frequency Response20Hz-20KHz
PlugStereo mini plug + balanced 2.5mm
WeightApprox. 23.5g

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Scores Scores

FiiO BTR3K Scores

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Full technical specifications

FiiO BTR3K Full technical specifications

reported by FiiO



Color Available



About  58×25×11mm





Volume Button


Transmission Distance


Status Indicator Light

RGB light indicates the input Bluetooth audio codec, charging and working status

Hands-free call/Mic


Call up Siri in iOS




Audio Input

Bluetooth connection (Bluetooth 5.0)

Supported Audio Format(s)



Not Supported

Mic Function


Headphone Output

3.5 mm stereo jack

Headphone Balanced Output


USB Port

Type C USB

Volume Control

Side buttons

Status Indicator Light

RGB light indicates the input Bluetooth audio codec, charging and working status

Charging Time

≤1.5 h (DC 5V 500mA)

Power Input

Recommend DC 5V, 500mA

Battery Capacity

330 mAh

Drive Ability

16~100 Ω (recommended)

Output Power

About 25mW (32Ω loaded)
About 78mW (balanced)

Frequency Response

20~20kHz(aptX connection)
20~40kHz(LDAC connection)


122dB (A-weighted)


≥ 118 dB(32Ω loaded)

Bluetooth Chip



Type C USB charging cable*1, Quick Start Guide*1, Warranty Card*1,Clip*1

Battery Life & Test  Conditions (The test result is based on specified test conditions and just for reference)

Battery Life

About 11 h

Bluetooth Transmitter



With set output at 40mV


FiiO BTR3K Photos

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