You could post in the IEMs Discovery and General Discussion thread. I’m sure some of the IEM experts here like @antdroid, @prfallon69, @toranku, among others, can help you out.
The trick with IEMs is that fit and comfort are immediate and important considerations, especially given the diversity in people’s anatomies and, more specifically, the shapes and sizes of ear canals. Those IEMs that work for some will be useless for others. You’d need to figure out which kinds of tips suit you (silicone, foam, etc.), as well as their sizes, and whether they’re to be inserted deeply or shallowly into the ear canal.
The next issue is that there are millions of budget options under $100, almost too many to choose from, but that the range of options narrows as you go up the price scale. Given that you’re coming from the HD 6XX and have an LCD2-C, you’d do well to skip over the budget ones and look for those in the $100-400 range. Strangely, there aren’t that many in the mid-fi price bracket, say $400-800, but there are many high-end contenders, especially from $1100 and up.
There are three main types of IEM driver, each with its own set of characteristics, advantages, and limitations: dynamic; balanced armature; and hybrids (typically pricier and a combination of the first two, although nowadays with other kinds as well, some of which are still new tech).
There are multiple options for sources but since you’ve got the Mojo, I’d stick to that and figure out what people recommend as an IEM that has a good synergy with it.
I’d suggest starting out by posting in the general thread with info about your budget and then your sound priorities and preferences and seeing what people suggest. IEMs, as you note, could be ideal for your needs, especially when it comes to resolution and being able to discern the details in your music. Good luck!