Spotify has been streaming 1411kbps for most tracks through their browser player in Chrome and only then I notice little difference between Spotify and Tidal HiFi. The Masters tracks still are noticeably better than the Spotify on Chrome app playing at 1411kbps.
There is an upside to streaming from the Spotify Chrome app for 1411kbps which doesn't incur extra cost but this is all functionality Spotify is not advertising. The downsides are this only currently works in the US (IIRC) and navigation in the Chrome Browser app is very limited compared to the desktop app.
I'm very surprised you were not able to notice a difference with such a great stack as the HD800s + Mojo and suspect it was something else in the chain limiting the potential. I suggest giving even just Spotify direct in the Chrome webapp a try again if not Tidal and ensure you have the chain configured properly.
You cannot compare bitrates directly like that.
1411.2kbps is uncompressed CD audio, while the 320kbps is a highly developed and advanced psychoacoustic format that aims to be completely equivalent to CD quality to the human ear.
So it's not "getting less than 1/4th of the music", like some audiophiles claim, based on faulty or non-existent understanding of audio codecs.
Also, you are absolutely not getting 1411.2kbps from the Spotify Chrome app. That is simply a display issue, or the actual decoding happening at another step in the chain, and it's either giving you Ogg Vorbis at 320kbps or AAC at 256kbps.
In the end, Spotify's content discovery was worth more to me, but if they finally release some lossless version for twice the price, I'll be happy to subscribe. Even at that price, one month of Spotify is stil cheaper than the first R.E.M CD I bought in 1991.