@Guillaume.
I really like the Tidal iOS app - looks good and works well.
You could use AirPlay to stream Tidal from iPad to your Devialet via an wAirport Express or Apple TV using Toslink cable into the Devialet. I tried that and it works well but the SQ is not as good as Tidal on Mac/AIR
Edit: just saw your post - I would guess it would sound better via Totaldac than direct to D800 but might be worth trying the latter.
I really like the Tidal iOS app - looks good and works well.
You could use AirPlay to stream Tidal from iPad to your Devialet via an wAirport Express or Apple TV using Toslink cable into the Devialet. I tried that and it works well but the SQ is not as good as Tidal on Mac/AIR
Edit: just saw your post - I would guess it would sound better via Totaldac than direct to D800 but might be worth trying the latter.
IMac macOS 10.15.3 (no link to Devialet ) / MacBook Pro Retina OS X 10.14.4 / Linn LP12 / Devialet 200 / Wilson Benesch Discovery.
Qobuz Desktop Latest Version / Audirvana 3.2.18 / Audirvana Remote / iTunes 12.9 / AIR 3.0.4 / Wi-Fi / FW 8.1.0 / SAM 50%
Cambridge, UK (Updated 27th February, 2020)