I did not see a follow up on the it03 or A4. Can you reference a post number?
It was in one of the other Trinity threads (the "What the future holds" one). I have tracked it down and chopped the comparison text below - please bear in mindv these were quick snapshot comparisons as I was up to my eyeballs in Christmas chores at the time I was writing them. Will polish them up and add any additional thoughts when/if I get time to write up my impressions properly in the Head Gear section.
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Some quick comparisons between the prototype Master and the LZ-A4 and the IT03 - these are pretty quick as I'm trying to get multiple things written up before Christmas kicks in properly, so will revisit properly when I am pulling my impressions together on the Master into one coherent "review":
LZ-A4 – the LZ-A4 is a tunable IEM in the low to mid-fi price range from the Chinese IEM manufacturer LZ, retailing for c. £150-160 at current exchange rates, putting it in the same price bracket as the Master. It has two different tuning filter parts (back plate and nozzle), giving a total of 18 different tuning variants. For comparison purposes, I have compared the sound with my favourite filters on both (red/black and black/red on the A4 and silver undamped or gold damped on the Master). The A4 has a crisper overall presentation than the Master, sounding slightly sharper in the treble compared to the smoother and slightly warmer sounding Master. There is a bigger sub-bass presence on the red/black configuration of the A4 compared to the silver filters on the Master, which concentrate more on the mid-bass. In terms of soundstage, the A4 feels slightly more 3D (or “holographic”, with the sound presenting all around the listener. In comparison, the Master presents sound outside the head, but in a more “box-shaped” environment which reminds me of a studio listening room (difficult to put into words, but that is how I’m hearing it). In terms of build quality, the A4 has an all metal shell and precision build, and looks a little like a car turbo sticking out of your ears in comparison so the sleek crescent moon shape of the Master. It fits comfortably enough, but is definitely less ergonomic and comfortable in the ear than the Master for my particular anatomy. The LZ-A4 is easier to drive than the Master, requiring a few less notches on the volume on my Hifiman Supermini to match volumes. In terms of technicality, both sound reasonably well matched, although the A4 seems to just have the edge in terms of separation and micro-detailing. Both IEMs are definitely in the same quality bracket, with the A4 tipping it overall for me with the enhanced sub-bass and marginally higher detailing and 3D imaging – it is a pretty close call, though.
Ibasso IT03 – the IT03 is a triple driver hybrid from DAP manufacturer Ibasso, and is their first foray into the IEM market. The IT03 comes in a black plastic shell moulded to resemble a custom IEM, with a contoured fit that “locks” in place in the inner ear. They currently retail around the $250 mark online, so are slightly more expensive than the Master but in a similar price range for comparison. The IT03 are slightly easier to drive, requiring a few less notches on the Supermini to achieve the same volume. Detail levels are similar, with micro-details feeling slightly more apparent on the IT03 due to the slightly warmer presentation of the Master. In contrast, note “edges” on guitar chords feel cleaner on the Master. The IT03 sounds more airy than the Master (using silver or gold filters), with a crisper feel to the treble and slightly more recessed vocals in direct comparison. The IT03 has more sub bass emphasis on the basslines compared to the more midbass-centred Master (on silver or gold filters). In terms of soundstage, both have a similar width, but the IT03 seems to have more vertical extension to the stage, leading to the airier feel to the sound in comparison to the more closed in sounding Master. Fit is similar, with the Master having an easier to fit ergonomic shape but the IT03 offering better isolation due to the shape of the shell filling more of the outer ear. Cabling is thinner but still good quality on the IT03 compared to the heavier-duty fabric cabling of the Master, and the IT03 uses the standard MMCX connectors compared to the Master’s bespoke design. Overall, another close match – the IT03 lacks the tuning capability of the Master and has a slightly colder sound with a larger sub-bass tilt to it, which will appeal to fans of a more neutral signature. The Master has far more flexibility in terms of tweaking the signature, and a warmer and slightly fuller sound through the midrange, but trades in some airiness as a result. It is difficult to call between these two, with the IT03 winning for me for tracks where I need their excellent sub-bass and cleaner feel to the sound, and the Master being preferable for more acoustic and singer/songwriter music.