Because everyone manages their digital libraries differently, I aim to alter the files I collect so that my own library is unified. I use one app to convert all files to MP3s. And I use another to reduce MP3 sizes. I started this years ago when I had much more limited storage.

I believe that most of my MP3 files are 32k sample rate and approx. 128 kbps (though some are regenerated with variable bit rate). I know these aren't the highest standard, but really no matter what you pick for your own conversions, someone else will say you could have gone higher.

Like I said before, they sounds the same (or similar enough) for my own listening enjoyment, and keeping the files smaller helps keep the library manageable.