I will ask this question completely unrelated to phones.
When I purchase and download music from Amazon the end of all songs are clipped off! I do use the latest version of Amazon music downloader. I am down loading to my Dell Inspiron laptop with Windows 7 Pro.
I do not have that problem downloading onto my phone or tablet using the Amazon music app. I haven't used the desktop download tool for them in years so I can't help you there. Sorry, just posting a possible plan b scenario