Well some quick impressions. I managed to get a used pair of XBA A3 from japan for a more than reasonable price.
As a former MDR-EX600 / 7550 owner, I sold those in hopes of one day getting an EX1000. Well years went on, and just when I was about to buy one, some head-fiers (props to
@Hawaiibadboy ) in the know promoted them here and on YouTube. That combined with their complete discontinuation by Sony means that they are exorbitant.
So I knew what I was getting into with A3, having kept up-to-date with what Sony was doing since the early days of creating the XBA series.
I definitely like these... but the bass.. it is too much. Ironically, a ton of bass is NOT great for high-quality electronic music. It is just too relentless. Like someone left the home cinema subwoofer on full blast.
With an IEM like the MDR-7550 you can safely increase the SPL get detail, get impact, and get that lovely dynamic driver bass. The EX600 was good too, a bit too rolled off on the low-end.
However, it is not all bad. Not at all. The XBA A3 are bombastic, but they are also excellent for timpani. This means for very dynamic music such as jazz and classical, the lower frequency percussion has serious impact. The 16mm dynamic drivers sound a bit softer and maybe not as integrated as they did in the 7550 to my ears. Perhaps that is the nature of the hybrid.
The overall tuning is not reference. This is more like very good home theatre. The sound is massive. Very open. An area where it exceed its dynamic brothers, is the top-end detail. Vocal are excellent. Pop music is exciting and borders just on the upper ranges of natural, never quite artificial but straying close. This is a very polished and exciting take on a mainstream sound. Sony's balanced armature design is very good quality, and really they seem committed to this and have made progress year over year.
It's like they mastered the dynamic driver in-ear and decided to give themselves a challenge. Based on the XBA-A3, I think it is an investment that is going to pay off.
I also have a pair of Etymotic HF5 (a poor mans ER4P, that is damn close), which is major bang of the dollar. Single armature, but tuned very well. More neutral and great value for those listening to dynamic music or who want more realism. It really comes down to what kind of experience you want. To me the 7550 hit the sweet spot - it was incredible with everything, and I actually feel the same about the HF5. The XBA is pure Hollywood - more razzle-dazzle, an impressive production.
So a bit of shade and criticism thrown at these. Surprisingly, these excel at listening to orchestral music, jazz, movie score, vocals productions, movies, etc. I don't think that was the intention. Of course, popular music productions, especially those with mixed instrumentation, are going to sound stellar. Vocals are spot on with these too... it just that bass.. a little too much Sony. Even a mixed hip-hop jazz production like Uyama Hiroto, that kick drum distracts. (note: I have listened to these a lot this evening, new toy syndrome, so for shorter listens the bass will be less fatiguing)
But hey, it could be me, I listened to a pair of Andromeda's the other day, and that was another headphone with too much bass. Everyone seems to love them, but it could just be a matter of high-price, expectation bias, and group think. They were great, and maybe I needed to spend more time with them, but for that price - no way. I also think at the full MSRP for the A3 (and I imagine the Z5) I would not want this signature - bit too much bloat.
So curiosity got me, as it does with this hobby/pursuit of sound. I'm glad to have these all the same. If I didn't have the HF5, I'd be trading these for a 7550 / 800ST
edit (couple hours later): After taking a break and coming back at them with fresh ears, they are better. They are just so full-on. But sometimes you want to experience music like that. This isn't an all-day headphone. It's something you put on for a while and immerse yourself. Also, low volume they are good, and the bass is balanced thanks to the Fletch-Munson effect)
day2: fresh ears.. okay. Definitely growing on me. This morning tested them out with some Drum n bass. And just for this experience alone, it is worth keeping. The low-rumble, the bass feels like it is creeping along the floor and up along the walls. My impression still stand, this is a guilty pleasure IEM - will please bassheads for sure, but also those looking for a more dramatic, impactful sound without sounding too processed. The simplest praise I can give it, is that it is very enjoyable with piano, with full body resonance.