Audio Technica AT-PHA50BT


New Head-Fier
Pros: display of codec used and bluetooth profiles, solid connection to phone, build quality, good microphone
Cons: 30 gram weight, instructions manual in japanese, a bit hard to operate without looking
I purchased this little device after reading the great review by unknownsolo. I also have a Noble Audio BTS that I have been using every day for the past 6 months. This is an amazing little amp is dead quiet when connected to my IEMs, and compares really well to the BTS in that low noise floor. I tested with a silent audio file and there is a really minor hiss when it plays, but I can't detect this when there is low volume music.
I was looking for a solidly reliable device and the resemblance of this amp to a wireless mic helps to send the impression that some very significant engineering went into it's design. At about 30 grams it is light but has a very rigid feel and heft to it. The display is mirrored, and that looks cool but makes it a bit hard to read in the direct sun. The body is slightly textured and the buttons have a decent tactile feel.
The display shows the codec and bluetooth profiles on the display when connected, and there is indication when the device is receiving audio or data. This is really useful in troubleshooting connections to a laptop, or a phone. Bluetooth can feel like a dark art when it does not work and this helps to clarify when things are working or not. When a song starts playing you will see if it is using AAC or APTX on the display as well as hearing the quality difference.
The device seems to hold connection to my phone while playing audio and I have not had any audio corruption when using ITunes, VOX, Overcast, or Audible apps on the iphone. I play a lot of audiobooks and podcasts, and I have had problems with the audio skipping and dropping out when I first started playing it with other bluetooth headphones and adapters. This device did not have any issues during that startup phase or during the playback. VOX allowed me to play some lossless audio, and I was impressed with this even as compared with a directly plugged connection. 
Multipoint seems to work decently, but it is unclear to me how to switch devices or which take precedence. It seems like if I connect to the laptop first, then connect the iPhone it will be connected to both and the laptop audio will take precedence. I wish that were a little more clear. I have connected the amp to a Plantronics BT300 usb dongle and used that to make the device act as a headset for my Mac. I It will pause audio that is playing on the phone when audio starts on the laptop. The BT300 does not seem to use APTX but the audio quality is okay for a VoIP phone call.  When I use the built in bluetooth on the Mac it will use APTX and the quality is great and loud, but this is a less reliable audio path for use as a VoIP phone headset.
Unlike the BTS, there are distinct track forward and back buttons and that is a big help. There is also a lock switch that will prevent inadvertent button presses, which I have not yet needed but I think it will be useful. 
There is a separate snap on clip for attaching the amp to a pocket, and because I have a very short cable for my IEMs, I can keep it clipped to my shirt pocket. This also has the advantage of placing the microphone close for taking phone calls.
The microphone is of good quality and seems to work well on phone calls. This will require significantly more testing, as this will be one of my primary uses for the device. The mic gain is higher than the BTS and it seems to have some built in gain control to keep the sound in a decent range.
Overall this is a good buy, but I do wish that Audio Technica would officially bring it to the US. I expect a lot more interest in this as Apple ships the iPhone 7 and folks look for alternatives to use their expensive cans and IEMs. You can grab the japanese manual from the audio technica's japanese site and run it through google translate, and it gives you a mess of text but it can help with functions. 
@canonlp I'd like to test the bass roll off difference if you have a recommended song or sound sample that might really exercise the difference.
@agrosash I have been testing these with a pair of custom fit reshelled UE 10s. Compared to an unamped wired connection, the sound is louder and clearer to me for both the iPhone and Mac. I would like to test against a wired amp at some point, but I don't think I'll have one to play with soon and I might spoil myself. 
@logich: that sounds fantastic! thank you
let me know if you wanna buy my SB X7 LE for cheap and like new :)))


Pros: Sound Quality, Size, lots of features, lightweight
Cons: Independent volume level, no way to check the volume level before playing music
I have posted a more detailed review on my blog with hi resolution pictures.
I stumbled upon Audio Technica’s AT-PHA50BT little device that seems to offer exactly what I need. Even though this device was only released in Japan, there are plenty of sellers on Amazon and eBay that are willing to ship it to the US. At the time of writing this review, there weren’t any online reviews that I could find about this product (except for the very few Japanese ones), I decided to write this review hoping that it might help somebody else on the same boat. I decided to try my luck with this little device and let me tell you, I am not disappointed at all.
View attachment
When I opened the box, I was really surprised by how small this device is, very tiny. Build quality is really good and solid. Exactly what you would expect from a reputable company like Audio Technica. The volume rocker clicks in place when you turn the volume up or down. It does not make any noise, but it just has a little snap to it to keep the rocker in place instead of freely sliding left or right.
In the box, you will also find a small micro USB cable for charging, a small clip case, and the user manual and a device registration paper.
Looking at the AMP, the power/lock button and a USB charging port are on one side. Four other buttons, effect/call, play/pause, skip forward, skip backward are on the other side. Everything is clearly labeled in English. The front LCD screen is very nice and bright. You can see the battery level of the device, volume level, call history, and icons that show up at the top of the technology being supported with the device it is connected to. In my case, I had it synced with my iPhone 6 so it showed me HFP, A2DP, AURCP, PBAP. You also can see on the screen what is currently playing on the phone, band and song info. Obviously, everything on the screen is in English. The device supports showing names in Japanese. I haven’t had the chance to try that, let alone understanding anything.
View attachment
Sound Quality
I purchased this little device not to improve my sound quality. I have a pretty good home setup that I am happy with. I only wanted something more convenient for on the go. I was going to be pretty happy and satisfied if it had the exact same quality as plugging in the headphones to the phone directly. Except, having this now I can clip it to my shirt or put it in my pocket while using my phone freely.
When connected to my iPhone and sending music through the AMP, and since the iPhone also supports AAC, the AMP displays “AAC” on it’s screen. I am not sure if it will change the sound quality if paired with a device that does not support AAC or aptX. I also do not have any aptX device at the moment that I could try the AMP with.
Keeping in mind, I only have a small library of music stored on my iPhone. I mainly stream my music from iTunes Radio and xbox Music. When I first tried it, I couldn’t believe what I was hearing. I instantly became very happy. I kept switching back and forth between the AMP and phone and I could not tell a single difference. Could it be because of taking advantage of the AAC feature?
I mainly listen to modern and classic Rock and some classical music. Classical music sounded slightly little more crisp when connecting to the phone directly without using the AMP. I had to switch back and forth few times to be able to tell a difference. Then finally deciding that connecting to the phone has a slight more crisp sound to it. It’s not big, maybe only better by 5% when connected to the phone and not using the AMP. Definitely not a deal breaker. Also, I really didn’t notice the difference at first and took me many tries back and forth to be able to tell.
The AMP also has built-in sound effects engine. It uses AM3D that has four modes “Flat” which is the normal/pass-through mode without making any changes to the sound, Acoustic, Vocal Boost, Bass Boost, and Virtual Surround. I don’t like any of the sound effects and just keep it on Flat the whole time.
Overall, sound quality is really as good as connecting the headphones to the phone directly using AAC. I would love to try aptX one day and see if that makes any difference when listening to classical music over AAC. Will update this review if that happens.
One thing I really dislike is having two independent volume levels. The AMP does not control the phone volume. The AMP has its own volume and when turning the volume up or down, it only changes its own volume and not the phone. Also, there is no way to see the AMP volume level BEFORE starting to play your music. Not sure who came up with that idea.
View attachment
Final Thoughts
I am very happy with this purchase. I could not have asked for more out of this little device. Solid build quality, lightweight (only about 29 grams), lots of features, very small and easy to commute with, and sound quality is as good as plugging my headphones to the phone directly. Charging the battery barely takes 3 hours and play time is about 8 hours. I definitely recommend this if you are looking for a small adapter for the purpose of making your wired headphones wireless. The AMP also has built-in microphone for making phone calls if your headphones do not have a mic.
I just got one of these and have been really happy in comparison to the Nobel BTS, with exception of the weight. The connection is stable and the range seems to be very solid with my iphone 6. 
I'm using it with the Shure SE846.  Immediately noticed the hissing when there is nothing playing or during the 'silent' start of a track.  Once the music picks up you don't notice it anymore, there is a very noticeable difference in separation compared to the iPhone 7.  Wheres you get perfect dead silence on the iPhone 7.  It's a trade off I guess
a couple of points:
* The PHA50's presentation is very layback. It might be voiced toward earphone/IEM use, sounds quite nice with my Earsonic SM3 IEM, no "in the head" feeling.
** PHA50's "virtual surround" effect: turn on the effect and the sound becomes a lot more spacious, probably from all the micro-reverbs added into the sound, a nice feature for playing back-ground music while performing other tasks.