If you obtain a book on the High Seas, is it safe to use Kindle as the Epub reader? Would it phone home to Amazon that you have an "otherwise obtained" book?

I've been using Clipgrab (macOS) to download music (mp3s) from YouTube. I've seen some mentions that the quality (real bitrate as opposed to what the file states) is bad to begin with on YouTube and that downloaders might make it worse. How bad is the quality of what I'm downloading? Any better downloaders or does the quality suck to begin with?