I have a KZ ZSN Pro IEM and it's been going strong for 4+ years.

I also have a cheap Bluetooth QCY IEM that I use for podcasts and when I don't want wires tangling me.

Whenever I change from the Bluetooth QCY to the wired KZ I am in awe. The KZ ZSN Pro is a blast to listen to. Specially metal. The definition, the sound of the bass drums, everything is clear and powerful.

So I decided to try some entry level open back headphones and bought the SHP9500 that was cheap on Aliexpress recently. I thought I would find it even better since a lot of people sang it's praise for the price, but I am underwhelmed.

I find my KZ to have way more definition and power.

Also I need to up the volume of my smartphone quite a bit compared to the IEMs. It is near max volume.

Of course they are different beasts and the IEMs are literally inside my head. I don't really know what I expected.

I'm sure beyerdinamic or other more expensive brands might be better, but I don't feel like going down that path.

I'm going to keep the SHP9500 for a week more to see if I like it for different situations, but for now I am not amused.

So I've just been using basic earbuds my whole life, never felt like spending big bucks on good headphones. Recently though, I've been really interested in what I've been hearing about IEMs. Youtubers and forum users have been name dropping a few of them, such as Moondrop Chu/Chu II, Salnotes Zero, etc. So I looked them up, and was shocked to find how cheap they are. They're like $20, in the same price range as the crappy earbuds I buy anyways! These kind of headphones seem like a whole world I know nothing about, with pros and cons I don't fully understand, so what would be the best recommendation for a first set?

I'm looking into the ATH-M40X, which seems to be the best below 100€, but i would like to know other tilders opinion :)

EDIT: preference to over ear and portable (portable is not a key feature that i'm looking, but it would be nice to be easy to carry around)