Tldr; Sensaphonics 3dme.
I've tried a bunch of passive "musician" earplugs including Etymotic, Hero, Eargazm, Erasers, Vibes, Alpine and Loop. Most didn't fit very well and were either uncomfortable or just didn't stay in place well. I tried making my own custom fit ones using Radians. But the bottom line for me, was that they were almost all a complete letdown in terms of sound quality. All I could really hear was mud. My cabs over the past few years have included Fearfuls and Audiokinesis Hathor and Changelings, so I'm not lacking in upper mid or highs coming from my stage amp.
The only ones that worked- stayed in place and were comfortable enough for a whole 3hr gig were the Loop. They work at concerts, loud movie theaters, etc... But still mostly mud in front of my rig (better the further away I get from it, but it's rarely all that possible).
So I started looking into going the custom fit Westone route... But I doing complaints about losing upper mids and highs. So next I researched the Etymotic active ones. But the complains about those were frequently around lack of adjustment, or any way to adjust the eq curve to your hearing sensitivity. In one thread, somebody mentioned the 3dme by [This invalid link has been removed] system. So I figured, why not throw them more money at the problem?! I mean how much is your hearing worth, right?? $800 apparently.
But are they worth $750 more than $50 earplugs? I mean for that price, why not just put that money into a set of custom fit IEMs and a wired amplifier? The answer is simple. They're SO worth it.
I can finally hear really well -with or without a monitor mix direct into them. The key is each ear bud has a mic. The body pack has a Bluetooth app to control it. That app let's you control the mic audio level, eq the signal, and most critically for me, it has a limiter. I can now hear everything in perfect fidelity at whatever Max spl I choose. And I can hear my bandmates talking between songs without having to take out an earbud. There's a line in for a monitor mix, and if you have access to a wireless iem receiver, you can just patch it into the line in.
It's absolutely amazing. So much so, I think it's the best bass purchase I've ever made.
The only real Achilles with the setup are it dependence on an internal rechargeable battery, and the property earbuds / connector (due to the mics built into them). The stock ones are dual driver. There's a "pro" or "tour" upgrade model with quad driver buds. Sensaphonics offers custom fit gels for either model, but they just slip over the universal fit bud. So far I'm totally happy with the Comply foam, but I'm rarely doing any singing.
Sorry for the super long thread derail in which I suggest a massively more expensive solution... But it just works SO freaking well for me, I figure I should share it.