Thanks for the thoughtful response!
That makes me very curious to try the AirPods Pro 2, since I’d previously assumed they probably weren’t far off from the Buds2 Pro.
Unfortunately I’m not an Apple user so the APP2 are somewhat crippled feature wise from what I understand, but maybe if they sound good enough they might still be worth it. (Or, god forbid, they make me consider switching to Apple.)
So, as far as I know, the main features you’d be missing on Android are gonna be Spatial Audio and dB monitoring. Otherwise you still get ANC and transparency mode. Anyone in the thread can feel free to correct me, as I’ve never owned an Android (and thus this is hearsay).
How wide is the nozzle?
5.37mm as measured by DMS.
I got these IEMs about a week ago, and I have mixed feelings. It probably has more to do with my limited experience with IEMs in general and high expectations set by positive reviews.
In terms of tonal balance, frequency response and timbre this IEM is amazing, one of the best things I’ve heard so far. The mids are spot on, the bass comes in plenty, and the treble is perfect to my taste. The buss rumble is there, some punch, decent sound staging and great layering. But there is one “but” that my non-audiophile wife expressed better than me when she first listened to them: it just isn’t very engaging. I haven’t been able to decipher why exactly so far.
Maybe it’s because of the tips. I tried all the stock ones and all third party ones I had at home, none of them give me both the fit and the sound that I would enjoy at the same time. So I’m waiting for 2 more sets of tips to arrive to give it another try.
Do you think this “not engaging enough” sentiment could be mostly related to the neutrality (it’s hard to call an earphone with a strong bass shelf and pronounced treble “dead neutral”) or is it more common in IEMs compared to over-ear headphones? The best other IEMs I heard before are probably Moondrop’s Blessing 2 and Kato, and I wouldn’t call them very engaging either. My reference point is more like over-ear headphones: HD650 and Focal Clear.
Thank you. Unfortunately, I doubt that info.
The smallest IEM nozzle I’ve measured was cca. 5.6mm. However, there are numerous comments like “diameter of the nozzle … is a bit big”, “nozzle diameter is on the larger side but the length is short”, “metal nozzles are collared, wider than average in diameter”.
I’ve also found a claim that for Mega 5P, the widest part of the nozzle was 6.5mm.
So, if somebody has 5EST and a caliper tool, please enlighten us.
I don’t have a caliper unfortunately, so I just measured with the ruler: ca. 6.1mm. DMS measured the nozzle in the middle, while the thicker part is at the edge, because it retains the tip. And yes, they are a bit thick if you ask me, so the “wide” tips that they come with sound good but don’t fit into my ears properly as they are too short. That’s why I’m waiting for wider and longer tips.
I get what you are saying. The tips that really woke them up for me are the moondrop mis foam tips I used with the blessings. Maybe worth a try.
The reviews of these IEMs looked very promising to me. DMS released his ode to Mega5EST exactly when my wife was visiting their hometown - Chengdu, China. So, I pulled the trigger on them and a few days later my wife came back home with this nice souvenir.
As I shared above, I was a bit confused in the beginning whether it’s my thing. Recently I took the Mega5EST to the Munich Hi End 2024 and used it as my reference IEM there. After the trip and rolling a gazillion of eartips I can give it a better review.
TL;DR: Hisenior Mega5EST is a great Harman-like-slightly-V-shaped reference IEM that can do a fantastic job if you find the eartips that make these IEMs shine for your ears. I would appreciate a bit less sub-bass and a tiny shift towards mid-bass though.
Tonal balance
Well, you can see the frequency response measurements in the posts above and it sounds like it measures.
There is a plenty of sub-bass. If you don’t get it, then the seal is not working, try larger tips. It’s not crazy overdone and most people will find the bass of this IEM very pleasing. To my taste, the sub-bass shelf is actually the main issue of this earphone: it masks the mid-bass, and because of that the bass does not feel so punchy and controlled as it potentially could. I haven’t tried to EQ it, but it would be interesting to see how sub-bass reduction would change the character of these IEMs.
The mids are pronounced, clean, and clear. The vocal-centric tracks is probably not the main reason to buy a V-shaped earphone, but Mega5EST is good at vocals too. Depending on how the track is mixed, it is capable of reproducing them as “in your head” as well as “out on the stage”.
My favorite part is the treble though. This is where the preferences may vary the most I guess. To my taste, Mega5EST gives me exactly what I want: a strong treble presence without excess energy, lots of detail without sharp spikes, and nothing that I would complain about (i.e. sibilance). The cymbals sound like what they are, the brass shines and sizzles like you are in a Jazz chamber. I was listening to several over-head e-stats at the show, and the little Hisenior was on par with the better tuned ones in the treble region.
Detail retrieval
This IEM is perceived as very detailed. Acoustic information is present evenly across the frequency spectrum, there are no areas where it rolls off or misses something. Now add perfect layering in the mix, thanks to the tri-band design.
In busy passages with fast transients and a blend of high and low frequency phrases this IEM keeps doing a great job where many other headphones and IEMs give up and produce an indistinct mish-mash. In slow pieces with strings or brass you can feel the texture and tiny vibrations.
This quality together with a good tonal balance is what I guess makes others say that this $500 IEM outperforms many >$1000 IEMs, which it really does.
Punch and engagement
This is not the punchiest earphone, but it can do a pretty good job at hitting your eardrums and making you tap with your foot, if you find the right eartips.
Earlier I complained that Mega5EST sounds very well balanced but somehow distant and not very engaging. Some posters here commented that this can be fixed with tip rolling, and I confirm. After a lot of trial and error I found the tips that liven them up for me.
Sound staging and imaging
Is also very tip-dependent. Some tips make you hear everything like the sound drilling inside your head. Some other tips open everything up and put the instruments in space around you holographically. With some tips it’s somewhat in the middle.
Amplification
Sorry, what? Aplification for IEMs? Yes, an Apple dongle or a standard 3.5mm output on your laptop won’t do it for Hisenior Mega5EST. At least because it comes with a 4.4mm-terminated balanced cable 
For IEMs they are not super-sensitive, which means you can experiment with the pairing a bit. I found them to sound very pleasing on the new Aune S17 class A amp. Significantly wider and more musical than my Questyle M15 dongle that I was carrying with me.
Tips on tips
Try a lot of them. Different tips will work for different people. E.g. the best ones for me so far were the ML-sized tips from A&K Zero2, but for my wife they sound too much “in the head” and don’t feel comfortable. For her, the M-sized Kinboofi silicone tips did the trick.
The stock tips are a miss IMO. The “wide” tips give better staging, but are too shallow, so that for my ears there is no punch and the IEMs feel like they can fall off any time. The “narrow” tips are a bit longer, but the narrow hole ruins the sound stage for me. Both silicone tips are very thin and give me some weird resonances in bass region. Foam tips - can’t say anything about them, they just don’t fit in my ears.
The nozzle is indeed quite wide - it’s 6.1mm or even a bit more in diameter in the wider part at the edge. I’d go for wider inner diameter and denser silicone material for the tips in general with these.
So, if it doesn’t work out of the box, try other tips from third party. I’m still waiting for Divinus Velvet tips to arrive.
Divinus Velevet tips have just arrived, and OMG do they make a difference!
Overall they change the tonal balance quite significantly towards more V-shaped. The bass is boosted even more, but is more clean and articulated than with other eartips. As a result, with these tips the Mega5EST slams the hell out of you. Such a change of character!
Highs are also boosted. It is still not so harsh as with inherently bright tuning, but I’d say that’s on the edge for me. Of course, it helps with even more perceived detail and soundstaging effects. But if you’re treble sensitive, these tips are not for you.
Like always, more V-shape means less focus on mids, and that’s a downside of these tips. If you’d like the mids to be more present, I’d say go for Kinboofi tips instead - they are more balanced and are a safer bet in general.