Are there proof that spotify normalize audio at -14LUFS?
I did some empirical A/B comparison between mp3s donwloaded on my pc and audio streamed on spotify.

I choosed this quite loud songs on pourpose:

http://variety.com/2016/digital/news/spotify-soundcloud-acquisition-report-1201873039/

Apple CEO Tim Cook, right, hugs Beats by Dre co-founder and Apple employee Jimmy Iovine at the Apple Worldwide Developers Conference in San Francisco on Monday, June 8, 2015. The maker of iPods and iPhones announced Apple Music, its new, paid streaming-music service to launch this summer. (AP / Jeff Chiu)

I was about to upload my music to TuneCore who would then distribute it to iTunes, Spotify, etc. and noticed that they said to make sure my music was in 16 bit format. It was my understanding that 16 bit is just for burning CDs.