Once you are in Spotify site, go to 'my music' at the bottom right. Upper right hand corner, there is 'setting' a wheel like icon. Click that. Then go to 'music quality'. It gives you choices and choose 'extreme'. If you want to download, it takes long time just like Tidal does, but streaming is more or less unchanged.
thanks for the comments.
As for quality difference between Tidal and Spotify, unless you go to 'extreme' setting, there is definite difference, I agree. Not much when you go extreme on Spotify.