Tidal have implemented the results of research by Eelco Grimm into the optimum way to implement loudness normalisation for streaming services:
http://productionadvice.co.uk/tidal-normalization-upgrade/ (http://productionadvice.co.uk/tidal-normalization-upgrade/)
The original paper:
https://octo.hku.nl/octo/repository/getfile?id=qLlZPGSVXFM (https://octo.hku.nl/octo/repository/getfile?id=qLlZPGSVXFM)