I purchased the Fiio BTR15 in December for $110 a few weeks after I purchased the BTR5 for $105 as I believed the BTR15 was not to be released for an additional year. See my review on the BTR5 [here](https://www.reddit.com/r/headphones/comments/1c11iwc/fiio\_btr5\_review/).
For some of my background, I have been delving into headphones for roughly two years, semi-active in the r/headphones subreddit. The BTR5 & BTR15 have been my first "high-end" DACs. The BTR15 has also been my first and only entry to balanced audio which I have tested with various headphones and cables.
First impressions & Unboxing:
All of Fiio's boxes are extremely high quality and nice to look at. I've found myself collecting them, and that remains true here. The box has a beautiful shine to it and feels extremely high quality. The device is wrapped carefully in a soft plastic bag/cover to keep it safe during shipping. Adding to this, the entire interior of the box is soft, high quality die-cut foam keeping the device and it's accessories from moving around. The rest of the packaging is all paper/cardboard keeping plastic waste down. I could see reusing the box for storage of the device if you are putting it in a drawer and don't want it getting damaged.
Fiio BTR15 Unboxing
Fiios instruction booklets are so amazing as well. I know packaging is meant to attract the customer and I'm getting baited in, but I like it.
Fiio sends a fairly short (although this is mostly intended for phones) USB C-C cable. I do not believe this is a one-way cable like the BTR5's was - that was always very odd to me, but this one is two-way which is fantastic. In the bag is also a USB C-A adapter because the tech industry failed the migration to USB-C. Nice that they include this in the box. I would have preferred seeing this either without the zip baggie at all, or at least a paper/recyclable pouch for them if necessary. The accessories are already in a separate smaller box, so why the baggie?
With the power off I can see the screen easier than I could on the BTR5. See the pictures for reference. The BTR5's screen is completely invisible, and honestly any random user may not know which way is up until powering it on. Sure, the screen is tiny, but it's invisible, even when on. The BTR15's screen is visible when off and when on. I'm not sure how this happened as some of the marketing of the BTR15 focused on the "new" OLED screen compared to the BTR5. Maybe it's due to the BTR15's screen being slightly inset compared to the BTR5's?
Fiio Screen Comparison (BTR15 Left, BTR5 Right)
Keep in mind these images don't fully capture the small size of these devices. Both are only 7cm tall and 3cm wide. I could comfortably fit a few of these in my palm, so when I point out the size difference of the pause/play button, it is roughly half the length.
Software & Interface:
I greatly preferred the earlier BTR5 as the interface felt less cluttered, even if less intuitive. The menu is now a scrolling menu compared to the paged menu used on the BTR5. This results in easier navigation for users, however, more controls to squeeze into the already limited interface (Power, Play/Pause, Volume Rocker) to operate opening the menu, selecting a menu option, opening said menu, making the choice, and navigating back. I preferred the BTR5's "on/off" menus for the most part as I felt more complex operations can and likely would be handled in the app, not on device. I prefer quick-menus like this to be for quick settings, not for things like language settings, power functions, and mode toggles. That said, the larger screen certainly demonstrates the ability to expand on the menu.
Of the menu options, there are the following: "Charge Protection, Gain, Filter, EQ, Car Mode, USB-Audio, Dimmer, Off-Display, Language, Reset". Of these, I feel things like the charge protection, car mode, USB mode, dimmer, display timeout, and language could all be in the app. I figure most people are not going to be changing these constantly, whereas things like gain, filter, and EQ could be changed on the fly - hence the quick menu. Resetting the device could also just be a keypress shortcut, not a dedicated menu option.
Menu operation is similar to the older BTR5 using the power button to access the menu, the volume rocker to select the option, then the (smaller this time around, more on that later) play/pause button to access a menu, and the power button to go back. After a few times this becomes intuitive, and I don't see many using this menu on a regular basis. Most using this device will likely use the app through their phone, or using a "set and forget" method.
A point that bothers me to this day is the delay for power functionality. The BTR5 is approximately 1 second of holding the power button to turn the device on or off. However, the BTR15 is roughly 3 seconds. It feels long enough that I often find myself wondering if it has charge, has an issue, or if I pressed the button right in the first place. This could likely be shortened in a software update which Fiio has been great about (more on that later).
Outside of the power button options, the remaining controls have a lot of customization. Toggling the operation mode for skipping tracks between pressing or holding (which in turn toggles the volume operation), or toggling the method of operating the settings menu are all available in the bluetooth connected app. This app requires no account or login, which is amazing in today's world of constant connection. The app could use some UI work for overall design modernization, however, it gets the job done and keeps the settings in easy to find places. Nothing is hidden from the user here.
Software updates can be done over bluetooth this time around, compared to the older BTR5 which required downloading the firmware file from Fiio, using a USB cable, and updating that way. I do wish the app had an indicator of an update. Currently you must check periodically to see if an update is available, and those can take a while over bluetooth (upwards of 10 minutes).
The play/pause button is significantly smaller this time around (see images to compare) making it more difficult to find when in a pocket or otherwise out of sight. I often confuse this for the power button when attempting to quickly pause (or more likely play) a track after an interruption. While partially used to this after several months, I prefer the BTR5's interface. This must be due to the new power option switch, yes? Well, seemingly not as the volume rocker is just considerably shorter than the BTR5's, leaving a large gap between it and the switch. Why? I'm not sure - this could be anything from poor thinking to lack of hardware flexibility.
Fiio Interface Comparison (BTR15 Top, BTR5 Bottom)
No NFC on the BTR15 which the BTR5 had. Like I said in the BTR5's review, I have never used it and I doubt this will be a deal-breaker for anyone thinking about purchasing this device.
Battery Concerns:
Anyone who read my BTR5 review would know I had concerns about the battery protection then, and was sorely disappointed in the limited (and just plain poor) design of it. The BTR15 adopted some options from the larger, more expensive BTR7 with the hardware charging switch compared to the BTR5's software "Do you want to charge?" option. The issue with the BTR7 (from my understanding, I do not have a unit yet) was similar to the BTR5 where it basically required charging to function. It was just the BTR5's "NO CHARGE" option, meaning it would use the battery when acting as a USB-DAC/Amp, and when drained it would die. The BTR15 fixes that quite well with the new "PC" mode which sets a maximum charge to 80% and will operate through DC (?) when reaching the limit. This should greatly lengthen the life of the battery if used long-term over USB. Would I recommend leaving the BTR15 plugged in 24/7 as a USB-DAC/amp? Certainly not. This is still a lithium-ion battery we're looking at, and it can/will expand over time with poor battery care. I would have preferred some options in the mobile app to maybe set the charge limit lower, or even to something like "0%" and just have it function as a USB-DAC/amp without ever touching the battery. If this device still requires battery power to function, it may not function at all when (not if) the battery ceases to hold a charge. I imagine it would simply flicker on and off, that is, if the battery doesn't press against the screen like the iPod Nano when it expands.
Continuing with this, the battery charge level does not exist when not in "PC" mode. Worse, it must be *on* to make this function. Simply switching it to "PC" will not activate the charging limit - the device must be on while charging to limit at 80%. If you have the device off, or in any other mode, it will charge to 100% and I have no idea what battery protection is in place here. I use a 5W charger to charge this and it is often slightly warm when I take it off the charger, meaning it may be attempting to overcharge? I am not certain. A way to test this may be using a USB voltage tester and monitor the charging. If the device is still drawing power (particularly the same/similar to normal charging) it would be overcharging. I do not have one of these devices yet, but if I get one, I will attempt to update this review with that correction/confirmation.
The power-saving issues I noticed on the BTR5 are similar here. The device will properly power off if disconnected from any device. However, when connected and no audio playing, it will stay connected until either the source device closes the connection or the BTR15 runs out of battery. This is likely not great for the battery, especially for people who may want to take naps with their device, or forget to turn the device off before putting it down/away. They may come back to find a dead device when they want to listen to music. This may also increase the number of charge cycles on the device. The device *should* detect no real audio input signal and power down after 5-10 minutes (or again, have a setting in the app for this). Budget wireless IEMs do this, why not a $110 bluetooth dac/amp? The device should also have a firmware controlled charge limit for those who want to sacrifice some battery life for longevity, especially in a device most will not be repairing/replacing batteries. I wish I could simply set the device to 80% or even 60% for all modes and it will flat out stop charging at that value.
Connection Options:
The switch on the side has three options - "PC", "BT", and "PHONE".
The "PC" option I have talked about above. It's primary function is enabling high-quality USB connection to a laptop or desktop over a USB connection. I have not tested if this works on consoles. I am not sure why it wouldn't assuming something like USB headphones would work, however, your mileage may vary. The other function is limiting battery charging to 80%, again only while powered on - no firmware-based protection. I believe this mode is supposed to disable bluetooth connections, however, I have had inconsistencies with this and I have needed to disconnect the device from my phone sometimes, particularly if it was connected over BT while I enabled "PC" and plugged in the cable.
Watching the screen change with the current sample rate is amazing for context and ensuring the USB connection to the Tidal player is working.
The "BT" option operates as the BTR5 did, charging when plugged in regardless of power status and will enable bluetooth pairing. This still allows USB connections, however, when used on my android phone I have had issues with the device bootlooping like it is attempting to connect over bluetooth and USB simultaneously. Again, this has been inconsistent. I have also attempted to use this mode while charging the BTR15, so plugged into a USB wall adapter, and using bluetooth for the connection. This failed to work once, then worked fine a few days later with the same charger. Ymmv.
Finally "PHONE" is similar to the BTR5 just with charging disabled. It will not charge when connected over USB to a device, however, this is also not running on DC power. The point is to drain the BTR15's battery, not the source device, while getting a high-quality USB connection.
These modes get weird when you want to use the built-in microphone though. Sadly, don't expect to use your in-line or boom mic if you have one. The BTR15 will only use it's in-line mic over bluetooth. Naturally the audio quality takes a large hit over this protocol, often sounding like a phone call on PC. You may not be using this to chat with friends - the most I would recommend is the occasional phone call. Adding to the PC mode, the mic is completely disabled in PC USB mode. Yep, that's right. Somehow a USB DAC with a built-in mic has no mic capabilities over USB. If you want a phone call, you must use bluetooth for this device, and then you'll want to clip it to your shirt so the mic is in a good position. Although, it did not sound awful when just sitting on my desk - again, over bluetooth.
Build & Durability:
The device is amazingly built again, just like the BTR5. Full aluminum chassis/frame, thick curved glass front and back, it feels very premium. The plastic clip is identical to the BTR5's which I figured was fine. I use both my BTR15 and BTR5 during yard work to power some 3M WorkTunes (The radio version can take an AUX cable) and have had no issues with the clips. Sometimes the device can get tugged out of my pocket if I snag the cable, but I attempt to tuck it away to prevent this. I will add the AUX jacks - both balanced and unbalanced - are incredibly sturdy and the device will often hang from the cable rather than fall on the ground. A+ Fiio. They knew this was going to get caught on everything from clothing to doorknobs and made a durable headphone jack.
I much prefer the 4.4mm balanced port over the 2.5mm port on the older BTR5. Thicker plugs have always felt more durable both during use and misuse. I do not feel like the end is going to snap off, worst of all, leaving the broken part stuck inside my device rendering the port useless. USB-C again, just like the BTR5, and A+ for that.
The buttons feel amazing again. They are almost identical to the older BTR5 in every good way. You can be certain when you press a button. Also no noise whatsoever when pressing buttons with sensitive IEMs plugged in.
I am not sure if the glass is Corning Victus or something similar, but I have kept this in my pocket with my keys and occasional pocket knife and I see no visible scratches or damage to the glass. My Corning Victus 2 glass OnePlus 10 Pro has a scratch on the screen somehow, and my Fiio BTR15 has none - good job Fiio!
Sound:
The BTR15 was my first step into balanced audio as I only had 4.4mm cables when I had the BTR5, which is 2.5mm balanced. This port made my Meze Classics 99s and modded Grado SR80e's light up with detail. Separating the audio into separate amps is such a cool step to push more power. I need more power-hungry headphones to really test the capabilities of this device, however, it feeds my AKGs just fine. Oddly enough, those 3M WorkTunes I mentioned require a higher volume than my AKGs. Mind you, this is all on the low gain setting - I have not needed the high gain yet.
Tidal has also found it's way into my digital arsenal, the first app that's been able to take control of my BTR15 and alter the playback rate per track. This is also my first introduction to MQR audio, which I am exploring. So far, I prefer FLACs which I suppose is not a surprise to anyone. However, my old hardware could play flacs - not MQR files. While I prefer FLACs on my desktop which has much more storage, and is better fit with my new Fiio K7 (look out for that review) my phone does not have 8TB of storage.... MQRs are great for that when I want to download playlists of hundreds of tracks (I know those are rookie numbers). This means I can have mostly high-quality audio with a fraction of the size requirement. It may not be perfectly lossless, but if you're listening over a bluetooth connection lossless audio sort of goes out the window.
I primarily use the BTR15 with my balanced Grados, Mezes, and IEMs. This is over bluetooth and wired connections for my laptop. I no longer wish to use a headphone jack again - I want to always have this little device nearby. A simple 3" USB-C cable and you have a fulll-powered DAC with bluetooth capabilities if desired or needed. Using bluetooth to walk around town, the USB when at the library or coffee shop is amazing, and the simple switch helps for jumping between modes.
The EQ settings are a bit more intuitive on this device compared to the BTR5 (the software options are just better overall) however I never found myself playing with it much. It is in-depth, but I could not use LDAC with the EQ settings and I would prefer quality over EQ, especially considering I can do EQ in most apps today like Spotify.
Firmware Updates:
Fiio has done a great job keeping the device updated. When I first got it there were some minor issues, however, a month later I received an update that fixed those issues. On the other side of that coin, it sometimes brings other "issues" (depending on your perspective). For example, when I first got the BTR15 it would automatically turn on and off when being used in "PC" mode and plugged in/unplugged from the USB-C cable. After a firmware update, that functionality is gone. There were also issues with battery charge limits between "PC" and "BT" mode where the device would sometimes charge to 100% regardless of the mode, however, that has been resolved in an update.
Perhaps a notification in the app may be useful. The app could use some work in the design category, well this is true for all Fiio devices as they all share the app.
Conclusion:
If you are in the market for a portable, powerful, and extremely affordable DAC/amp, this is the best choice I have seen. An alternative may be the Qudelix 5K which I have not reviewed yet. The Fiio is extremely well built, very duable, full of features, and flexible for most users. If you are getting this and online communication is important to you, this may not be the option. This is purely meant for consumption, not communication.
Edit: Added measurement context to first-impressions.
