3M earplugs are fine for blocking noise in general. But all foam ear plugs block more noise at the treble and mid ranges better than in the bass. For live music, that means that the sound will end up being very muddy, with way too much drum and bass, and the vocals, lead, and rhythm guitar will be mostly gone. Etymotic is specifically good for audio settings; you're getting less overall noise reduction, but it's keeping the sound more clear.

I think that bass in particular is hard to block because at least some of the sound it through conduction rather than air movement in your ear canal.