Please don't hate me kind zZounds employee! I felt a divine purpose in this one.This is my first purchase of a "Hi-Res" audio device, aside from studio equipment. I wasn't able to find any reviews or real world info on this device but it seemed to fit the bill of what I wanted and with the Audio Technica name I felt it would be better than most. After a week of use with Shure 215s and Sennheiser HD598s as well as in the car and through my desk monitors I'm on the fence with this one, but again, first device of this type so maybe it's my expectations that are making it difficult. For reference I am using my Note 8, Google Play, Tidal, and LDAC as the source which may not be the best but this is my experience with the PHA55BT. My daily listening at work is with SkullCandy Method Wireless, so the lack of hype here may be causing me to be unsure. You be the judge.

Sound
The first time I heard the amp I was impressed with the difference. While not as forward, it was wide, open, and clear. An acceptable trade off. Highs were crisper, almost hyped but not annoying. We'll say sharper. The bass was clear and accurate as well although lessened, much like I would expect from a monitor and I can live with that. I've enjoyed this amp on both the 215's at work, being much clearer on dialog and around the house or running errands with the HD598s for the sound stage. I signed up for Tidal just to really test this thing and while I can't say anything definitive… read more about using Tidal's "HiFi" files there is something there that makes the experience more enjoyable, something subconcious perhaps. It's not the night and day difference of fringe distrotion we hear in 128kb/s music versus 320kb/s mp3's, but from 320 to 16/44.1 it's...more engaging, I'm more aware of the music. More believable, maybe fuller sounding? The difference is enough I would prefer the files from Tidal or similiar services, but not enough I would buy everything again just for the maybe 20% increase in quality-ish-ness.The original idea to even buy something like this came from the SkullCandy Methods inability to handle my mix files I was printing for reference. Once copied to my phone the Note 8 would silently compress and downsample them to compatability but playing from the laptop I record and mix on would not work. With the AT and 215s worked like a charm, and with the sonic characteristics I was able to reference as needed and study the mix elements, so another point for the PHA there. I tried different mixes in 16 and 24 bit, flac and wav, all worked like a charm and this lends to the amp being clean in it's reproduction as my mixes were darker and muddier (still learning) compared to my music library. In the car I have the stock radio and speakers but have added a JL Audio 10W7 in a sealed box powered by a JL XD 700/5 to round out the sound. Until I finish replacing the speakers and rewiring them to be powered by the amp I have no Aux In, so I use an FM transmitter, which most of us know is not great but better than nothing. The FM transmitter introduces static and is subject to interference, and worst of all has a low output meaning I have to turn the radio up more than I'd like to get decent volume but with a high very noticable noise floor during pauses or quiet parts. Enter the AT 55BT, using this as a preamp with my phone in a clamped windsheild mount the noise floor is significantly defeated and signal is improved greatly as well as quality. The most noticable difference here is the bass is stronger unlike in my headphones which I thought was strange. No distortion at all at full tilt from the phone and AT amp, making a much more enjoyable experience in the car as well. So from my trials, I find this unit to be good at what it does for it's intended purpose; a high quality bluetooth preamp. It's usefullness has me loving it and using it more and more, but I still have doubts.

Features
The unit is surprisingly small. Think Bic lighter, this thing is 1.5x the height and width, as thin or thinner. Light as a feather, perfect for the coin pocket on your jeans or even a shirt pocket. This lends to feel of it being well made, if you drop it it's too light to make a real impact, doesn't seem to flex, and the included clip protects the switches and buttons.The face is machined with an almost holographic Audio Technica logo which is for lack of better words, sexy. It's a very pretty device, nice to hold in your hand, the buttons are familiar the 3 lights on the front dance during operation and functions. It reminds me of Sony devices, how they have sounds and visual cues to add to the experience of the device. Very Japanese!I first used this as a normal Bluetooth device, paired it, plugged in and spent some time with it. I will say plainly that it will not push high end headphones, know this now. With the amp mode switch (mode A/B or gain Hi/Lo) there really wasn't a significant difference, only a slight boost in volume meaning that for the HD598s I had to turn my phone up into the orange (above 60-75%) which I normally would anyway but the fact I had to, to even start getting loud with the Hi gain option was disappointing but not a deal breaker. It definitely gets loud enough to enjoy and drown out ambiance but headphones that are 50 ohm or higher may not benefit from this amp. Conversely its excellent with IEMs. Probably my favorite use for it with the true 7 or 8 hour battery life I use it at work in a fabrication shop where it's very loud and the Shure's offer superior hearing protection over typical earbuds.Now I've been using it in LDAC mode which it confirms with a green light on the front. On the Note 8 when you pair them together there is a slider in the menu where you would forget the device for LDAC, you have to enable it. I also turned on developer options and forced AptX 16 and 24 bit, 44.1 and 48k to little or no imporvement over SBC. Probably because of the files themselves. But with LDAC enabled the phone transmits 32bit 96k by default, basically the difference between fiber and standard cable for internet. The headroom is there if you need it and can benefit you even if you don't. The problem I've encountered here is packet loss or audio/signal dropout. Intermittantly anyway, no disconnects. I have had this problem where if I kneel or squat down the bluetooth would become erratic with popping and CD like skipping, not very often but it happens. This amp seems to be prone to that. At first it seemed like the phone itself was having trouble processing the audio at that high of a level and do everything else it needs to causing artifacts but I've had it happen when handling the amp and even my headphones, coincidence maybe but it's happened often in a short period of time. It bothers the crap out of me but not enough I want to send it back because it doesn so well in so many places. Just something to be aware of. When I receive the device everything looked in order except that there was a small plastic film/bag in the bottom of the box making me think it had already been returned and maybe it's just this unit is iffy. Hard to say.While I'm sure using LDAC reduces battery life I'm not aware and the amp uses a normal micro usb and probably does best with .5-1 amp blocks so charging is easy. I would recommend that the batter be excersised for this type of device if you want it to last and you should at $120. Drain it completely and charge it completely to excercise the cells as often as possible. The included clip seems strong and fits snug while still being easy to remove and leaving controls easy to access. The buttons are plastic with raised labels in a typical layout and function to most bluetooth headphones letting you control volume, skip, play/pause, and answer hang up calls. Obviously I can't hear the microphone but being Audio Techinica we can assume it's a better than average condenser with a good pick up range you don't have to hold near your face to be heard, and again, I work in a loud shop and have been able to clip it to my shrit collar and keep working while talking on the phone. The signal range is decent enough but not impressive, expect 30 to 50 feet before it starts to break up and even sooner if there's a wall between you and the transmitter. Not really a deal breaker considering it's purpose.

Ease of Use
Plug and Play. One option switch and audio controls, pairs quickly by it's model name, and produces great audio!

Quality
I don't see this thing breaking unless subjected to extreme stress like being run over. It's so light and small it's tough without trying. While the main body and clip are plastic I don't have any fear of damge but the machined aluminum face would be a shame to scratch. The headphone jack holds onto the plug well without being grabby, no issues while moving around or handling the device even with a big 1/4 to 1/8 adapter sticking out of the top! Although with the clip attatched the adapter is just shy of sitting down all the way. This doesn't affect the signal but means it's not properly seated and more prone to being pulled out but no issues so far.

Value
This where I stay on the fence. With all the options on Amazon as the Audiophile market grows it was a tough call. I went with this unit because Audio Technica is popular for a reason, their products are loved, tried, and true. There's rarely a perfect, one for all solution with things like this but the PHA55BT checks a lot of boxes which keeps me from getting too upset about it's hiccups. Like most things you can definitely go cheaper at the cost of quality and functionality, and you can spend more for materials and small improvements. As with most of my purchases I find this to be middle of the road, the sweet spot. A brand with a solid reputation for quality and performance making a well equipped and very convenient device, I took a chance on this unit and the more I use it the more I value/appreciate it. I definitely don't want to downgrade but would not spend a penny more for something like this. So I apologize for the length but I know studio and producer types will look at this as well as "audiophiles" who don't know the jargin or specs, but this unit can be great for anyone and it's not cheap so this is my best effort to inform because I searched forums and aritcles to find little or nothing which is surprising considering the brand and level of interest in this market these days. I'm not an audiophile, I'm a home stuido operator and live sound guy on some weekends but I love music and want to hear it on the level (bada pssh).If you can afford it BUY IT. If you're just interested in a solild, high value BT receiver for you >$150 headphones, this could be great but it's not necessary. You decide. I took a chance because I'm a brand loyalist. I'd like to buy the PHA100 DAC but again, the price. That's Apogee and Universal Audio territory. But maybe, just maybe, Audio Technica has something to prove in this growing market.

Manufacturer Support
None to speak of yet.

The Wow Factor
Wow I actually bought this, no going back now lol now if only I could find some real world info on the PHA100 DAC, I could have the matched pair and that would be WOW. You know, because a e s t h e t i c.Seriously, I would buy this again.

Musical Background:
Home studio, live sound, jam man

Musical Style:
Metal, rock, blues, the works read less