Sony XBA-4 Review

The quad driver flagship of Sony's XBA series 

Specs:
Driver: Quad Balanced Armature 
Frequency Response: 3Hz~28KHz
Impedance: 8Ω
Sensitivity: 108dB
Cord Length: 1.2m / J-Cord
Plug Type: L-plug
MSRP: $349.99

Packaging / Accessories:  
My previous Sony IEM, the MDR-EX600 had exception packaging and presentation; the XBA-4 (and the entire XBA series) certainly meet the standards set by Sony's other line of in-ears. The packaging of the XBA-4 looks great and the IEMs are nicely displayed. Unlike the EX600, the packaging of the XBA-4 is actually reasonably sized. Inside, accessories include 7 pairs of sony hybrid tips, a cord adjuster, and a very nice magnetic clasp carrying case.

Build Quality / Appearance / Cable:
For a product at this price range, I was a little disappointed to find that the housing are made of plastic. They are extremely light and has a chrome finish, but all this makes the product feel a little cheap. Despite this, they do feel sturdy and are well constructed. One thing to note is that the housings are bulky and one of the largest I have seen on universals. I was again disappointed to find the cable  undetachable, but this simplicity in design clearly shows the XBA series being consumer oriented. Sony at least provide great strain reliefs that should prolong the life of the cable. The cable is semi-flat and relatively thin. I understand there are different versions of the XBA-4 - I have the North American version without the iPhone controls and with a 1.2m j-cord. Personally, I prefer y-cords but the j-cord can be convenient when you only have one earpiece in and the other can rest on the shoulder. 

Comfort / Isolation: 
To my surprise, the XBA-4s are extremely comfortable when worn cable down. Maybe I am just lucky to have ears that fit, but they are definitely above average in terms of comfort for me in comparison to the other universals I have used. When worn with the cable over the ear, I did find the nozzle a little too short for them to stay in well, and as a result the housing do fall out once in a while. Isolation is very good as with all closed balanced armature designs. 

Sound: 
The Sony XBA-4 produces a spacious sound with a strong bass presence. They are not designed for professional use and the sound is clearly geared for consumers. With the presentation being far from neutral, there is emphasis on the mid bass as well as the treble. While this will appeal to many people, the XBA-4 does not sound natural to my ears and the quad drivers lack coherence. 
Lows: Since the design of the XBA-4 contains a woofer, and a "super-woofer", it comes at no surprise that there is an emphasis on the bass. It is powerful and much higher in quantity than the majority of armature-based IEMs. The bass is full-bodied and weighty, but at the same time it sounds quite effortless with very good extension. Bass notes are rounded and can be a little slow, meaning that it is also not as tight and clean down low. With the softer note presentation, I don't find the bass to be aggressive at all. It does provide a nice rumble and bass will always be turned up one notch even in bass-light tracks. Within the bass, I do hear a slight elevation in the mid-bass that certainly adds to the "fun" factor. 
Mids: The midrange is slightly recessed and sounds a bit muffled. The color in tone is obvious and can often make the midrange sound unnatural, although the amount of detail present is still impressive. While vocals do not take center stage like on the RE262, they are just slightly behind the bass. Vocals tend to sound dry and lack clarity compared to others in its price range.
Treble: The top end of the XBA-4 is where I find to be the most disappointing. It is not bright, but there is a peak in the treble that makes it metallic sounding. This pronounced "shh" sound and metallic tinge makes it very hard to listen to the XBA-4s for very long before the treble becomes fatiguing. In addition, instruments just don't sound right. With only average extension and air up top, the treble fails to impress. This is of course keeping in mind that the XBA-4 is a $350 product, not $100.
Soundstage / Presentation: Soundstage on the XBA-4 is actually quite large. It is spacious with excellent width, and conveys distance accurately. The pinpoint positioning is also impressive but that's where my positive comments end. Where I think the XBA-4 fails to deliver once again is the coherency between the quad drivers. As a whole, the drivers sound disjointed and artificial.  

Summary:
The Sony XBA-4 is the flagship of their in-house produced balanced armature series. Unfortunately, I feel that this flagship has major shortcomings compared to other similarly-priced in-ears. I can understand why they may appeal to many with its powerful full-bodied bass, but I do feel that at $350 the price cannot be justified by its overall sound quality. For me, it is the metallic treble and incoherency throughout the spectrum that makes it hard for me to recommend these over other IEMs with a similar sound signature.