Just picked these up used from a seller on eBay. Coming from several Audio Technica iem's I have to say that I'm glad I made the switch.
Before these I've owned, ath-ck10, ath-im03, dba-02, and a couple other lower end Sony ear buds.
I sold the im03 headphones because in my opinion they were too analytical and cold, while lacking bass. They were also uncomfortable after a couple hours of listening, and were a bit too harsh or bright for my ears. I mostly enjoy listening to Pink Floyd, and even for songs like those, the im03 were too bright (fatiguing and painful sibilance at times) and did not have sufficient bass.
After reading about these xba-a3 from Sony, they sounded just like what I wanted. I like the bass available from drivers, but love the detailed treble from balanced armatures, so when I found out that there were hybrid iem's it sounded like they would have the best of both worlds.
Hearing then now for the first time listening to one of my favorite songs, shine on you crazy diamond, and echoes, my immediate impression is just wow. When I first got my im03 I wasn't particularly impressed right off the bat, and subconsciously I knew I'd be selling them, which I wound up doing. These however, [xba-a3] are amazing.
The sound stage is expensive, if I close my eyes it feels like I'm in a giant concert hall; the bass is plentiful, tight, and controlled. The highs and mids are slightly recessed but very detailed and watery as expected from balanced armatures. Exactly the sound signature I was looking for. They're also very comfortable and with the smallest tips included fit perfectly. One note is that you will need FLAC or other high bit rate music as they're exposing flaws in the recordings.
I can see wearing these for hours without pain or fatigue.
The wires are admittedly thin, however they're very flexible and rubbery and the over the ear pieces are also very soft and comfortable. The wires themselves are very high quality, and while they don't look like they could take a lot of abuse, are so soft and thin that they're barely noticeable. Very refined.
They look great, sound amazing, and are comfortable. I think I've converted from Audio Technica over to Sony. The reviewers are right, these are extremely under rated and for the price are excellent.
Edit, two days later, all I can say is that Sony has made a masterpiece with these earbuds... The bass alone compare to the im-03's is enough, but their incredible soundstage and crisp, detailed mids and highs... I want to buy a second pair just in case these ever break...