Wireless Experience

The FiiO BTR5 as a Bluetooth receiver and DAC/amp is how I suspect most customers will use it since wired-only options can be had for less, including from FiiO with the older E17 Alpen I still adore and use. The BTR5 uses the excellent Qualcomm CSR8675 SoC that has been rated highly and used in far more expensive wireless products. It relies on Bluetooth 5.0 and has integrated support for aptX, aptX HD, active noise cancellation, and Qualcomm TrueWireless stereo. There is native 24-bit audio processing courtesy the Kalimba DSP, and this is also how FiiO managed to get the dual microphones with cVc 8th gen noise cancellation, which works surprisingly well, too. This tech is also available with an in-line mic, and the BTR5 switches to it automatically. Pairing to a Bluetooth device is trivial, and it immediately brings up the available codecs as supported by both the BTR5 and source, including Sony's LDAC on my android phone, which is really where wireless performance shines.


For those who thought that perhaps the on-board menu was too much to work around, FiiO has a first-party mobile app called FiiO Control available for both Android and iOS. I can't speak for the iOS app, but see many negative reviews on the Android platform that seem to be a clear case of PEBKAC, with several users not understanding that it is a complementary app to hardware and doesn't do much by itself. I had no issues whatsoever using it with the BTR5, which itself is not a brand-new device either, so perhaps any bugs at launch got ironed out over time. With the device paired to your phone/tablet that has the app installed, FiiO Control automatically detects the BTR5 with a thumbnail on the home page and then leads you to the device-specific controls. This includes the ability to rename the device or reset it to the factory default, as well as whether or not to charge the BTR5 when connected in USB mode as a DAC or even reverse-charge your phone in wired mode. Car mode is best used, well, inside a car or similar, where you want the BTR5 to turn on with power and turn off when the USB power is off. This way, you will have the BTR5 connected to your car speaker system in Bluetooth or wired mode and not have it powered on and slowly draining the battery of the car in addition to ruining the battery longevity of the BTR5 itself. You can also choose the Bluetooth codec of choice for audio, which will depend on the source device.


There are many who think using an equalizer for higher-end audio devices is heresy, but I personally don't see any issue in it. After all, no company will be able to completely match your needs, and a finer EQ control with 5–10 points of customization is often more than a software DSP can do. FiiO does exactly that with the BTR5 allowing 10-point EQ, but not with LDAC because of Sony things. The Qualcomm SoC allows full EQ everywhere else, and we see some preset options for various music genres covering a range from 31.5 Hz to 16 kHz in nearly 2x increments over 10 steps. There is also a custom preset, but you can easily customize the others as well. Play around with it, especially if your headphones aren't meeting your specific needs completely, but be aware that not all headphones respond well to EQ. You may end up with worse signal/noise ratio resulting in the loss of some details, as well as audio depth.


A handy guide has been included too, which also goes over some things you may have struggled with, including how best to remove the BTR5 from the case/clip once installed. I appreciate these small notes that add to the user experience, and then there are far more technical choices, including an estimated load that has the app suggest the desired output from either the 2.5 mm or 3.5 mm ports. This is because the BTR5 supports its own volume control that is separate from the source, allowing you to keep the source volume maxed out for the best signal strength to the BTR5 to then use the FiiO Bluetooth amplifier with its sixty steps of volume control and two gain levels (Low and High) for the best-possible listening experience. Note that things can get really loud, so FiiO starts out low by default. One thing that did irk me is the need to press the volume button for every single step—there is no option to hold it down for a more rapid volume adjustment as with most such devices. Perhaps FiiO is erring on the side of caution lest you accidentally damage your ears. Then there are the low-pass filters that pass on signals with a frequency lower than a selected cutoff frequency and attenuate signals with frequencies higher than the cutoff frequency. There are several presets too, with the exact frequency response dependent on the shape of available filters. Also present is a channel balance slider, as well as harmonic compensation and distortion compensation options, and a DAC clock divider option I haven't seen in a while on such small portable devices. By default, it is set to 1/4, which is fine for Bluetooth mode, where battery life is also a consideration, but set it to 1 when in USB mode to make full use of the on board FPGA clock management for improved signal quality courtesy the 45.1584/49.152 MHz dual crystal oscillators for both Bluetooth and USB modes.


So what is actually driving the digital to analog conversion and powering the two outputs? I mentioned before that FiiO has two DACs in place, allowing the 2.5 mm balanced output to get more than decent power to drive headphones. The DACs in question are the flagship-class ESS Sabre ES9218P for wireless devices, allowing 32-bit/384 kHz sampling over stereo output with its Quad DAC technology rated for an SNR of over 122 dB on the balanced output and >118 dB with 3.5 mm stereo on the BTR5. Total harmonic distortion (THD) is so low (under 0.003% even on the 3.5 mm output) that it is a non-factor even in wireless mode (with LDAC at least, other codecs will likely be worse). Channel separation is also impressive at 79 dB in stereo mode and 119 dB over the balanced output. I could cite more specifications, but the key takeaway is that the amplitude from the 3.5 mm port is a maximum of 1.8 V without load that drops to about 1.6 V at 32 Ω load, which corresponds to a power output of ~80 mW under the same load and ~90 mW at 16 Ω. This is plenty of clean power to easily drive pretty much all IEMs and a lot of headphones, but if you need more power, the 2.5 mm balanced output comes through with ~240 mW at 32 Ω. Take the gain setting into account as well, and configure volume and gain accordingly.


FiiO has the frequency response curves for the BTR5 as-is with an applied load under various wired/wireless use cases on this page, but such is the nature of x86 systems that there is simply no LDAC support or even aptX HD on the typically used Intel wireless chips. I don't have a handy oscilloscope either, but can say that there was indeed no distortion felt across the frequency range of 20 Hz to 20 kHz in wired/aptX HD, which goes up to 40 kHz with LDAC. So instead, I aimed to test more intensely whether the BTR5 changes the frequency response in wireless mode compared to my soundcard, and whether there is an improvement over the Realtek ALC3266 chip on my laptop. Testing was done similar to all other IEMs to date, as described here, with only the left channel measured to keep things in check.

We immediately see that even in the more basic aptX mode, relative to aptX HD and especially LDAC, there is a slightly elevated bass response compared to plugging the IEMs directly into my soundcard. In fact, it is more of an elevated V-shape response in that the mids are slightly recessed and the upper mids and highs are slightly boosted. I have an issue with this since I personally don't think a DAC/amp should affect the frequency response too much, but there is a whole class of tube amplifiers that generally just add warmth, so as long as you are aware of this, it is not inherently an issue. Things are the same in LDAC mode based on my listening experience, but there is just so much more detail there.

The wired connection straight into my laptop is absolute garbage by comparison, which to be fair could be said about most laptops. Your motherboard might well have a proper DAC/amp setup that is isolated from the rest of the PCB, but even so, the space and power constraints come into play even before any leakage from other PCB traces. This is why there remains a market for dedicated DACs and amplifiers even before going into niche cases, such as the recently announced and immediately sold out Audeze LCD-R current-driver ribbon driver headphones. I don't have a 3.5 mm port on my phone, but even using a basic Type-C to 3.5 mm dongle makes things worse. There are some aftermarket solutions with a built-in DAC, and at that point, you might as well get the BTR5 itself for increased resolution and detail even in wireless mode. I was also able to drive some beyerdynamic 250 Ω headphones off the balanced output, although that is on the verge of pushing things. Yes, it can do it, but not well. FiiO itself rates the drive of the BTR5 for 16–100 Ω on the 3.5 mm output and 16–150 Ω on the 2.5 mm output. Wired mode is better there, as you can also use the BTR5 alongside a pre-amp or standalone amplifier and don't have to worry about battery life.

Speaking of which, FiiO rates battery life at 9 hours for the BTR5, but that is under a laughably bad set of test conditions, including using the 3.5 mm output in AAC with the screen turned off and volume set to ~15–20. It quickly goes down to nearly half that with high gain and volume on the 2.5 mm port and LDAC mode, but I had an average battery life of around 6–6.5 hours with the 3.5 mm output at 30 on the volume slider with LDAC. Not too bad, especially considering charging will take just over an hour. I do wish quick charging was supported to make things better, and the battery capacity is of course dictated by the size of the device.