With a single balanced armature, especially for bass players, they will be a one way street to misery. You'll want an IEM with minimum or a triple (bass, mid treble), or what I would consider the minimum, a quad balanced armature (double bass, mid, treble).
Headroom is key. Balanced armatures are rubbish as bass... hence you'll want to ideally double them up. You can get hybrid setups (where dynamic drivers are used over balanced armatures), which will give you more bass, more headroom - but less fidelity.
Think of it like this, would you gig with a 1x10... or a 4x10? Of course, you'll want the latter for the headroom, so the bass remains, clear, free from distortion (even if you can't hear distortion, if it's present, it will fatigue your ears and you'll be tempted to turn it the volume - which defeats the purpose of inears).