I've found this to be true in practice though. I almost exclusively carry a decent set of sealing ear-buds for form factor reasons (they slip into my pocket) and the sound quality is just fine. Something about the way the little rubber inserts create a seal with my inner ear causes it to carry bass surprisingly well. When that seal isn't working (or doesn't exist, on cheaper hard plastic sets) the bass is nonexistant.
I suppose it's surprising because of the bud's small size, but then again, it doesn't need to drive that bass very hard either. That may help.
I guess I haven't tried enough earbuds to find ones that fit my ear canal well. I don't like the feeling of them inside my ears, so I stick to over-the-ear models.
I suppose it's surprising because of the bud's small size, but then again, it doesn't need to drive that bass very hard either. That may help.