I've been a fully over-ear headphone user for ages. Can't tolerate on-ear headphones. But I got my first IEM recently to dip my toes into it. I got the Truthear x Crinacle ZERO: RED based on positive reviews and fact that it was really low risk investment into the IEM world. Wow, what a pleasant surprise! For the $$ I'm really enjoying them. I like the overall tuning and the normal Medium size tips seem to work just fine for my ears. Given that info, what would be a reasonable next step/upgrade in the $200-$500 range? Thx for any suggestions.