changing the sound over 5 dB will result in unnecessary noises and static.
If your audio file is already at its maximum loudness, then further signal amplification will cause loss of sound data (it is called "clipping"). Good example of overamplified audio is john cena meme song. I also think that Mara Jade's and Ep III Obi-Wan sound files overamplified too.
If you want to visualize that, you can use any audio-editing software. I recommend to use audacity (it's free, open source and easy to use).
So, here's example. I have unedited sound clip, here it's track image:
Imgur: The most awesome images on the Internet
If you want to make it louder, you should "normalize" it (boost amplitude, until it's highest peak reaches certain border). If you don't want to have clipping, you should normalize signal up to 0db (positive value is always clipping, negative value is always within range).
Here's the result normalizing:
Imgur: The most awesome images on the Internet . Red stripe means clipping. Actually, it's fine if some of highest peaks cause clipping, you won't hear difference in quality as long as clipping regions are very-very short.
Next thing I recommend to do is to EQ your track. By this I mean to reduce all frequencies below ~120Hz and rise all frequencies above ~3k Hz:
Imgur: The most awesome images on the Internet (you don't have to go deep THAT much in reducing low frequencies , that's just my preference. -3...-7db are usually enough).
Final touch is reducing noise (this one can cost you quality if you do it wrong). First you should select region of the track which contains pure noise and while it is selected you should choose effect "noise reduction" (I don't know how if it's true name, my version is in russian, but it's menu looks like this:
Imgur: The most awesome images on the Internet) and press first button ("create noise template" or smthng like this). Menu will close. Then you should select all your track and open that menu again, but this time you should press "Ok", however I highly recommend you to reduce volume reduction (20db are too much sometimes). You can also press "preview" button to compare result of different option before pressing "ok".
There are audio examples in attachment, if you want to compare results by ear ("we got company" -> "we got company normalized" -> "we got company EQ + normalize" -> "we got company reduce noize").
