How much amplifier power do you really need?

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I am completely new to Audacity, I have just downloaded a copy this morning.  So I have not yet worked out the significance of the various parameters and similar.  However, I did manage to get this from the native Laptev Sea track:

I noticed that your FFT uses a larger number of frequency bins, which is a good thing as it gives much better resolution in the low-bass region you're interested in. In retrospect I should have done that in the spectrum I posted earlier. Having tried it I don't see any obvious difference between the native track and the MP3 I used before.