When you say "lush" you do mean a smoother, fuller, richer, velvety type of sound, correct? These descriptive terms what you're shooting for?
I ask because a lot of folks will readily suggest mid range strong earphones, but they may not necessarily be smooth, full, velvety in nature. They may be quite the opposite, upbeat, crisp, in your face, etc. If you do want the fuller, velvety type of sound, you will have to give up some level of detail. You'd look for a headphone that has good mid range and lower mid range emphasis but a softer presence.
It's useful to explain, in detail, exactly what kind of sound you want. It is helpful for others to provide options that actually have
that sound.
I personally haven't listened to very many earphones. I'm quite the greenhorn in the ear-fi world. I know audio and could point you to home or car audio options, just not headphones.
I haven't personally heard an IEM that sounds the way you want.