That’s the Million Dollar Question, and one that’s dependent entirely on people’s willingness to open wallets IMO. I think there’s an uneven application as well, where the focus tends to be more on channel matching specific units/drivers over adherence to the tuning, since imbalance is more jarring than a mistune along with the general variance in the drivers and crossover component tolerances. I personally feel that channel-matching should be at least +/- 2db up to 6-7khz for anything $300 and over and that tuning adherence, while I would LIKE it to be universal, should not have variances over +/- 3db up to 6-7khz for anything $500 and up. I do realize that this is idealized and not the world we live in, though, so it is what it is. If you can’t afford potential disappointment, then you shouldn’t be throwing any serious money around OR buy used units that have been measured or proven to be in line with what is intended as much as you can. I have had fairly cheap units with terrible channel matching that were then replaced with FAR better matching units (my Dark Phoenix, thanks as always to Elise Audio for handling that). Then, with stuff like my Symphonium units and STORM, I know that they painstakingly try to match everything as best they can (which, IMO, is necessary if you want to be a boutique brand).
The problem is +/- 2-3 dB in the right/wrong place can mean everything, depending on your ears. I got to hear Paul Wasabii’s Estrella which measure about 1.5 dB light in the bass and 2.5-3dB raised in the 5-6Khz range.
That would fall within your proposed QC tolerance but I can absolutely hear a difference between PW’s set and the final retail version I demoed from @VIVIDICI_111 for my impressions.
I would not have praised PW’s set the same way I did the intended tune, but with a simple PEQ around 5.2Khz, everything falls into place.
But you wouldn’t have caught that in QC…what do you do with that?
And I still stand by all of my praise, but I can’t guarantee anybody else my experience. Not that I ever could, in the first place
Its a tough one especially when your dealing with someone elses tuning and work.
Had some time to edit and upload today a rare double header!
The Dawn , hit all my happy places!
The Elysian Acoustical Labs Effect Audio GAEA
I know I’ve seen this graph before…
Interesting plateau!
Yup it’s a bit intense up there definitely not a all rounder!
WTF is that dip at 8k? Coupler artifact, I hope?
Judging by how early the dip starts and how late it rises for the upper-treble, looks real.
I think it is sounds like it, sounds strange thats for sure not to my liking anyway.
A nice budget IEM and everything I was hoping the EA500LM was going to be tuning wise.
I know a few people who love this IEM but not so much for me. It’s a niche tuning.
Big Mail Call day
My SSD Drive and Case for the new
Studio with Mac Studio
EPZ Audio Q5 Pro
TP35 Dongle
RevoNext RH-21
Cvj Love Yakumi
CCZ SOLO DC02 a new one from Keephifi
and last but certainly not least Kotori Audio newest creation the Zephyr
NVME + SSD Case is such a great combo. Got one from Ugreen (20gbps version) and the kingston KC3000 and running Linux via it atm.
The last one was the interesting one 
This case has a fan you can turn on/off 40mbps is blazing fast!