I have the AV7704 and it’s a solid HT preamp. I would definitely try the Wiim Pro and Tidal to determine whether it’s worth the difference. Personally, I typically utilize Spotify Connect from either my iPad or phone with this preamp and it sounds pretty good. I also appreciate the convenience of staying within Spotify and simply “Spotify connecting” to the Marantz without having to switch any inputs. Convenience and simplicity override ultimate fidelity in my situation.
I’m still waiting for Tidal Connect, but don’t think this is in the future anytime soon. For clarification are you going through HEOS to access Tidal or are you staying within the Tidal app and AirPlay to the Marantz? Apologies in advance if I missed that.