I have the Axil XCORs, and like them a lot. Some time ago, I was using them at the range, and forgot I'd turned the "sound enhancement" on. While they certainly took the "bang" out of my shooting (I believe it was my 7X57 that day), I was surprised I could here people giving impact corrections ("one inch high..." about 20 lanes over. That's when I remembered to turn the sound off. That was on it's lowest setting, so I'm sure turning up the volume would be helpful.
RE: the muffs, one of the things I learned in the oil and gas industry was that muffs lose their decibel rating when combined with glasses. In the oil and gas industry, the concern was safety glasses, but I can see it being the same with simple sunglasses. Plugs are preferred.