Here are some IEMs I reviewed that I think will offer the bass your looking for but with more audiophile refinement and less fatigue in the upper mid and treble regions.
https://theheadfijourneyman.com/2021/08/11/tin-hifi-t5-iems/
If you wanna step it up a notch and stay in the planar realm these 7Hertz Timeless IEMs ($220), which I also own, are excellent and will not give you treble fatigue unless your source components are overly bright.
https://www.amazon.com/Linsoul-Timeless-Earphone-Aluminum-Detachable/dp/B09C8GN9PQ
Hope this helps, and best of luck.