Fiio BTR3K Portable Balanced High-Fidelity Bluetooth Amplifier

Current Stock:
Wired - USB-C
Wired - 2.5mm
Wired - 3.5mm
Wireless - Bluetooth
aptX-HD Certified
MQA Certified

FiiO’s entry-level portable Bluetooth adapter, the FiiO BTR3K, is actually anything but entry-level. This small Bluetooth DAC, or even Bluetooth amplifier (it seems there are actually countless ways to name these devices), is one of the smallest in its category but it packs lots of interesting features that make it especially compelling. In a world that’s increasingly going wireless, for better or for worse, small devices like the BTR3K actually help in keeping the quality bar high without renouncing to convenience.

Design & Build

The current trend in the audiophile world is that of glass and metal for portable devices… which, incidentally, is just the same of mobile devices like smartphones and tablets. The FiiO BTR3K goes with the flow and sports a metal and glass body, with the four sides made of metal (presumably aluminium) and the top and bottom covered by a sheet of so-called “2.5D” glass (which is to say, a sheet of glass that’s thinner around the edges so it appears tapered). FiiO used bold, squared lines for this device and the result is a black slab that’s almost imposing. Well, it’s small so it’s not really imposing, but you notice its design.

The left side is clean, while the right side hosts the physical controls (power button, play/pause button, volume rocker), the lower side hosts the two jacks (3.5 mm and 2.5 mm) and the upper side hosts the USB Type-C port.

The metal and glass construction lends the FiiO BTR3K a feeling of solidity and durability; the materials are impeccably worked and the device is flawlessly assembled.

The thing that really surprises me about the FiiO BTR3K is the size: the device is so small it’s even smaller than the already small Shanling UP2 and, despite this small size, it offers balanced output. Apart from size, what impresses me is also the general design: it’s really clean and simple.

status LED is hidden under the glass on the front; it lights up the FiiO logo in various colours to indicate the current sample rate being played. It’s discreet and well done, without any light leak.

Features & Specs

Volume adjustment is independent from the source device, whether the BTR3K is connected via Bluetooth or USB. In both cases it keeps its own volume that’s distinct from that of the source; this is especially useful if your device does not have fine-grained volume levels.

Via USB the device supports decoding streams up to 16 bit and 48 kHz; anything above that will simply be downsampled so there is little benefit in using the BTR3K for high-res content. I tested using it with Linux and it works without issues; on Windows it requires drivers, while on macOS it should be plug-and-play.

There is a microphone on the right side which can be used to take/make calls when connecting the BTR3K to a phones; it works with PCs, too, but it doesn’t work when connecting the device through USB. The microphone works decently well, although it has to be kept near the speaker’s mouth to get the best results.

The FiiO BTR3K uses two AKM AK4377A DACs, which are specifically made for mobile applications (which have a very limited power envelope). It seems like FiiO opted for using the DACs’ integrated amplifier stage and this may explain the low power output. The added power available in balanced mode would also be explained by the presence of a dedicated amplification stage per channel.

Battery Life

It really does great in this regard and it’s downright impressive, especially once we factor in the diminutive size. With balanced output it’s a bit less than that (around 7 hours), but still quite remarkable.


The FiiO BTR3K can be controlled through the FiiO Music app, available for Android and iOS. It’s not really straightforward to get to the controls, as you have to scroll through the vast amount of items in the drawer on the left, select the device for connection (even if it’s already connected to the smartphone), then click on it once it says it’s connected. Apart from this access hurdles, the options offered there are reasonable and allow one to customise the device to their liking, including an equaliser and four filters.

Model  BTR3K Color Available Black
Weight About 23.5 g(incl. battery) Dimensions About 58×25×11mm (exclusive of back clip)
Audio Input Bluetooth connection (Bluetooth 5.0 supported) Supported Audio Format(s) AAC/SBC/aptX/aptX LL/ aptX HD/LDAC
Headphone Output 3.5 mm stereo jack Mic Function Support Bluetooth call, built-in omnidirectional microphone; support external microphone of CTIA cable
Balanced Headphone Output 2.5mm jack USB Port Type C USB
Channel Balance ≤0.1 dB Drive Ability 16~100Ω(PO)
Volume Control Side buttons 16~100Ω(BAL)
APP interconnection Supports setting through App Status Indicator Light RGB light indicates the input Bluetooth audio codec,charging and working status
Charging Time ≤1.5 h (DC 5V 500mA) Bluetooth Codes Display Supported
Battery Capacity 330 mAh Power Input Recommend DC 5V 500mA
Output Power PO about 25mW(32Ω loaded) Frequency Response 20Hz~20kHz (aptX connection)
PO about 50mW(16Ω loaded)
BAL about 78mW(32Ω loaded) 20Hz~40kHz (LDAC connection)
BAL about 40mW(16Ω loaded)
THD+N PO<0.003%(LDAC 1kHz A-weighted) Output Impedance PO≤0.3Ω(32Ω loaded)
BAL<0.002%(LDAC 1kHz A-weighted) BAL≤0.5Ω(32Ω loaded)
Noise Floor High power model& A-weighted
PO≤1.0uV BAL≤2.0uV
Amplitude PO:0.9V(32Ω /THD+N<1%)
PO:  0.9V (no loaded)
Low Power model & A-weighted
PO≤4.5uV BAL≤4.5uV
BAL: 1.59V(32Ω /THD+N<1%)
BAL: 1.8V(no loaded)
SNR PO≥119dB (32Ω  A-weighted) Crosstalk PO≥ 73dB(1kHz 32Ω loaded)
PO≥ 114dB(1kHz no loaded)
BAL≥122dB(32Ω  A-weighted) BAL≥ 108dB(1kHz 32Ω loaded)
BAL≥119dB(1kHz no loaded)
Sampling Rate Supported Up to 48kHz/16bit(USB DAC)  Accessories Type C USB charging cable*1, Quick Start Guide*1, Warranty Card*1,Back Clip*1
Chips Used DAC: AK4377 A* 2  , Bluetooth: CSR8675 
 Battery Life & Test Conditions (The test result is based on specified test conditions and just for referrence)
Battery Life Low Power model:BAL &P about 11h
High power mode:PO about 9.5H,BAL about 7.5H
Bluetooth Transmitter iPhone (AAC)
Connected Headphones M3 open earbuds(27Ω) Volume With set output at 40mV


1 year warranty from date of purchase. Headphones SG is a Fiio authorised reseller. All Fiio products purchased through Headphones SG is eligible for warranty.