The level isn't low, it's the full dynamic range of the gig captured. This is a good thing! The recording was normailsed to 0dB, so the quiet bits can't be made louder without clipping the loud parts, or riding the gain.
The effect you are hearing is quite normal in unmolested live recordings. Most commercial recordings (live or studio) have their dynamic ranges compressed considerably, so that they sound "loud".
I almost always have to turn the volume way up to get live recordings to sound right.
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