@Deezel177 already answered this for me and I agree with him. But still, I thought I'll make a post anyway. I apologise in advance for another long post. I got carried away.
As I said, TOTL is a casually over-used word. But before anything you got to ask, what do you really mean when you say TOTL?
As an audio engineer, I'm more inclined to value advancements in audio in terms of science, engineering and tech than just my personal subjective liking, which could very well be satisfied by a cheaper IEM if I didn't have the means to go above. It's also a battle I fight as a reviewer who prefers to review very neutrally for a wider audience than just audio engineers/scientists or people aligning with very specific personal preferences.
- Do you mean top of the line = flagship = most expensive IEM in a company's lineup? That could be a sub-$1000 IEM, as it is in quite a few lineups of a lot of very capable companies. But wouldn't it be snobbery to not call it TOTL just because it isn't priced exorbitantly?
- Top of the line maybe in terms of pricing? I could make an IEM that costs $300 to manufacture, something that took me 15 days - 1 month to do and price it at $5000. I could claim it has rare materials, took 2 years of R&D and needed special tooling to make in my marketing material to activate my loyal supporters who'd defend me any time anyone questioned my research. A sale of 1 unit per month could not only pay my rent but afford me a very comfortable lifestyle in a country of smaller economy. But would you be convinced it to be true TOTL if it pushed no boundaries?
- Or is it you referring to something to be at the top, the epitome, in its field or at least in certain aspects in its field?
When I personally think of TOTL, it has more to do with something that is/was groundbreaking and pushed the envelope of what's possible in its field or at least in certain areas of its field. One that did something so great that everyone learned from it and made it a benchmark for product development or as a reference in comparisons.
Let me give you a few examples. It's easier to talk about this with headphones, as ground breaking headphone engineering bloomed quite a few years before IEM engineering did - which even though more recent in the larger picture has managed to surpass headphone engineering in terms of ability to fine tune a signature to the last bit - something headphone engineering has been struggling with for decades. Haha
When it comes to IEMs, I'm sure everyone knows that there are a lot of extremely well-tuned IEMs even below the sub-$100 mark but it's the good technical performance that one needs to go quite a bit up in the ladder to achieve. Still, I'll state 2 IEMs that were groundbreaking for their time, one fairly well priced and a reference benchmark and the other a proper TOTL of its time that pushed boundaries and changed the scene, and funnily is still one of the highest sellers in the higher end market, something that has stood the test of time. No points for guessing - it's the Etymotic ER4 (SR) and 64 Audio U12t. ER4SR did a proper slightly sloped flat response speaker kind of reference tuning when other IEM manufacturers were tuning IEMs that needed you take out your flashlight and go looking for the upper-mids and treble that were lost in the jungle (looking at you Westone). Then there was the U12t that was quite groundbreaking when it was launched because it defined a balanced, sub-bass boosted reference-ish tuning and the kind of technical performance that could be achieved in an IEM, especially left to right separation and a roomy soundstage, when most other flagship IEMs were being tuned wonky AF left, right and centre! U12t is not a TOTL anymore in most aspects but still an IEM that is one of the easiest to recommend to new entrants in the higher end segment.
- Sennheiser HD600 - It was the HD600 that first defined what proper neutral headphone tuning could be at a time when most headphones were dam wonky. It was tuned to a slightly sloped flat speaker response and was groundbreaking for its time, a proper TOTL that pushed the boundaries of headphone engineering. It was considered fairly expensive at its time but is quite cheap now. It's not TOTL in terms of price or performance anymore but still one of the go to headphones when anyone asks for reference tuning, so good that it's still a high seller after so many years, even with so many good headphones launched since. A TOTL that lasted the test of time.
- Sennheiser HD800/HD800S - After HD600, HD800 defined how headphones could actually do a decent soundstage, something most headphones lacked, even the HD600. They were tuned to a bright Diffuse Field kind of sound, one that didn't hit it perfectly and needed a bit of EQ to perfect; to tame the brightness and sound more accurate, but it was its technical performance that defined what was possible in terms of a headphone's technical performance at that time. Not many headphones still can do HD800/HD800S level of technical performance, especially soundstage and separation. Ground breaking for sure. The attractive design and one of the most comfortable fits were a massive add on.
- Meze Elite - A headphone that I can call one of the TOTLs of today's time in terms of technical performance and fit. It's a headphone that has a coloured tuning, quite a nice one at that, but it's the technical performance again that is highly impressive - especially its grandness of sound, big soundstage for a headphone, left to right separation and space between every panned instrument. I of course EQ it to a neutral response and with that its technical performance shines even more and it becomes an even better headphone for my use case. This is again a headphone that has one of the most attractive designs, an even more comfortable fit, and is able to come closer to the speakers in a room kind of sound, more than most other headphones have. *Heads up - Review incoming!*
- Sennheiser HE1 - A full desktop system that could make you cry with its sound as well as price tag. If anyone hasn't heard about it, just google it and you'll see videos of grown men crying. Lol! This is a TOTL not only in terms of impeccable audio advancement a company has been able to achieve, be in hardware engineering, tonality or technical performance, but also in terms of pricing. I don't know of any other headphone that comes close to its level of performance or price tag.
Besides these, I try to avoid making lists or ranking lists of my personal favourite IEMs because I don't want to be seen as hyping stuff I've tried or reviewed as a reviewer and also because my top 5 list is always changing like crazy depending on what I get to use in the crazy chaos between production/recording work and doing the reviews in my free time. Also, a lot of my favourite IEMs are in the sub-$3k range, very few in the $3k+ range. I'm also not limited to IEMs as I have a production room in my house and I actually use my studio monitors and headphones a lot of the time due to the nature of my work. It's always a mix but I do most of the casual listening on speakers and use Headphones and IEMs generally for intense, sitting on a comfortable couch, discovering new music kinda listening sessions.
FINALLY!!! SOMEONE THAT RECOGNIZES THE MEZE ELITE'S TECHNICAL GREATNESS INSTEAD OF WRITING IT OFF BECAUSE OF TUNING!!!
Meze Elite supremacy!!! Especially with EQ! Not even every planar responds well to EQ, yet the Elites are truly something that does magic.