OK here is a comparison breakdown between the PSB M4U4, Sony XBA-Z5, HiFiMan T3/T5.
To start all 3 manufacturers have chosen completely different physical styles.
T3/5 use a hybrid half in ear design to allow for a large driver while still being comfortable. This design is comfortable due to it shallow insertion. This IEM is designed to be worn straight down but can be worn over ear if your creative.
M4U4 has a design that is more aligned with classical Shure/Westone IEM's but is a little more squared that those models with defined edges on the outside. This IEM is basically an over ear design for the cable. The smooth edges on the underside of the IEM help give a very comfortable fit.
XBA-Z5 has the most unconventional design of the 3 IEM's. It has an over ear cable that is designed to help hold the IEM hanging and then inserted in the ear. Most of the IEM body then sticks out from the ear. If you fashion conscious this IEM is
NOT for you.
Micrphonics are good on all 3 but the best is the Z5 with pretty much zero noise. The M4U4 is next unless your willing to get creative with the T3/5 and wear them over ear. But all 3 are above average in this regard.
Isolation is easily won by the M4U4 as it almost eliminates outside noise due to it design which fills your concha. Next up is the XBA-Z5 which offers surprising good isolation considering how it hangs out of the ear. Lastly is the T3/5 which is only average to maybe slightly below average for isolation due to its shallow insertion.
Wind noise - If wind is an issue where you live the Z5 suffers from wind noise more than the other two IEM's due to how much of the IEM stick out of the ear. The M4U4 is pretty much 100% immune to wind and the T3/5 had very little issues in this regard but was not quite as good as the M4U4.
Cables - all of these IEM's have replaceable cables. The Sony and the Dunu models use an MMCX design but the cables from both brands are not interchangable. The M4U4 has its own proprietary design that actually appears to be much more durable than the MMCX connectors. The M4U4 also is the only model that has an smartphone cable plus a standard cable. The Z5 on the other hand offers a standard cable plus a balanced cable. The T3/5 only had the one standard cable. Unfortunately I am struggling to find my other MMCX cables to test compatibility for this I AM. If I find my cables I will update the comparison accordingly.
I was thinking of doing direct comparisons of songs but I think I am going to start by just doing a break down of each IEM's signature instead because each model really has its own unique sound. I also want to address the other important factors of each IEM.
So I am going to start with the XBA-Z5 which is still my favorite. First and foremost this IEM is not for the faint of heart. To get the most out of it you have to use the balanced cable with a compatible DAP or DAC. For myself I settled in the Pono player. So when you figure out the true cost of this I AM I paid $630 for the IEM plus another $400 on the Pono. NOT A CHEAP SOLUTION! So while it sounds great and I may applaud it over the rest it is by far the worst value option.
Sonically speaking the Z5 is the ultimate bass lover IEM if you value midrange, treble, and presentation as much as the bass. It is the ultimate IEM for the audiophile with a bass head inside. It also has the most 3D like presentation I have ever heard in an IEM. If you want flat neutral bass avoid like the plague but for many others these would be the ultimate guilty pleasure.
M4U4 - this IEM is the most controlled and balanced IEM in this comparison. It still has bass north of neutral but It is the least bass oriented IEM. This IEM is all about the midrange with bass and treble as the supporting cast. This doesn't mean it weak or poor in the other areas it just means it shines the most in the midrange. This IEM also has excellent isolation so is great for public transit and noisy environments. It is the most traditional in regards to sound stage but is not poor in this regard just not as large or 3D as the other IEMs. Finally this IEM appears to be the least sesitive of the bunch requiring louder volumes and coincidentally one that benefits from added amperage.
T3 - the T3 is balanced but also very dynamic and bold in its presentation in all aspects of the signature. Amazingly it pulls this off without being shouty or harsh. Despite its lack of isolation I actually found this worked not bad on the train due to its boldness. But in a quiet environment I do find I listen at low volume levels. This IEM is a neck of a value for someone who wants a bit of everything. I was very happy with its 3D presentation and sound stage as well.
T5 - the T5 is much lusher sounding and warm in comparison to the T3. Unfortunately it's bigger bass and warmth was lost when used in transit unless I turned up to unsafe volume levels. But when used in quieter environments offered a more relaxed sound than the T3 which was better for longer listening sessions.
The Dunu's are the best value in this round up offering excellent detail and presentation along with rock solid build.
The M4U4 offers the best isolation and mobile use case. But they feel like they need more amperage than typical portable sources like a phone offer so they might be best for someone willing to use an amp or higher quality DAP/DAC.
The Z5 well, I think I covered the Z5 well enough already
.
Anyway I will try to do an A/B/C/D for maybe one song that incorporated all aspects of a headphone. But only if I can find the time.