To start, you could try either of these inexpensive options:
This is a review, listening tests and detailed measurements of Truthear x Crinacle Zero:RED IEM. It was sent to me by the company and costs US $55. I was relieved that they are more mahogany/darker red than what the name implies. Compared to the previous Zero version, they are supposed to have...
www.audiosciencereview.com
This is a review, listening tests, EQ and detailed measurements of the 7Hz x Crinacle Zero:2 IEM. It was kindly donated to me by a member and costs US $24.99. The cable is soft and longer than typical which I like. They take fair amount of effort to push it but then they make a reassuring...
www.audiosciencereview.com
They are both very close to the Harman target and will give you an idea of what that sounds like. You can then decide if you like this target, or, if not, what you don't like about it, too much bass, too little, etc.. You can also try using EQ to adjust it to see what you do like.
The Harman target curve is based on what most people seem to prefer and sounds "right" to most people, so chances are, you'll like IEMs with a frequency response that follows it fairly closely. However, it's not a hard and fast rule, and some people will prefer a sound that deviates from the target, to a greater or lesser extent.
Here is an illustration of frequency response that shows how an increase or decrease in volume at various frequencies effects the sound:
View attachment 344377
Borrowed from
@solderdude:
https://diyaudioheaven.wordpress.com/
hbb.squig.link
