Pros: Bass, detail, separation
Cons: Mids, build quality, and especially the treble, value
After picking these up from the Sony Store about a year ago, I can say that these are definitely not worth the $350-$400 price tag. Luckily, I picked them up for around $180 and to me, this seems like a more reasonable price for the XBA-4.
I really wanted to like these IEMs a lot more than I actually do. These were primarily going to be my pair for electronic music. I immediately discovered that these work extremely well with electronic house and heavy trap/bass tracks so it definitely hit the spot for me. However, outside of these genres, these earphones do not sound too good in my opinion.
I can immediately sense that the 4 BA drivers do a great job handling its own set of frequencies. But due to the fact that this headphone does not use any crossovers, the frequencies just don't blend well together. The advantage to not using any crossovers is that instrument separation is good and I can hear every instrument of the track independent from each other but they do not integrate well as it should for a headphone. The bass is extremely powerful and has a lot of body but surprisingly does not drown out the mids too much. However, the mids for some reason are extremely veiled and distant sounding (maybe I am too used to Shure's forward vocals). Therefore, listening to any type of track that has a strong vocal presence tend to sound "muffled". The major gripe with these headphones is the ever-so fatiguing treble. Which I will go into detail in the next paragraph.
Before anyone starts claiming that I do not have the right source (the XBA-4 at 8ohms is a very picky IEM). I paired it with a FiiO E07k which although far from an optimal source, have a low enough output impedance to drive the XBA-4 without a problem, Unfortunately, even hooked up with my E07k, the treble is way too harsh and metallic. Auditioning Steve Hoang's "So Incredible", the sibilance is so strong which renders the song completely unenjoyable. The fake and metallic treble really coupled with its distant midrange really makes for a strange sounding headphone which EDM lovers will rave about and listeners in general I think will find too fatiguing.
At the end of the day, I don't think these deserve the title of flagship and with 4 drivers I was expecting a lot more. I guess the low resale value coupled with struggling to retain its MSRP price is a direct reflection to the IEM's incompetence in the many aspects listed above. I see it listed on amazon still for around $250 I would avoid it at this price point. However, if you could get one under $150 and you are primarily using it to listen to EDM, I would recommend it.