Noob question about streaming . . .

You should be able to stream Tidal through HEOS in your Marantz. I have no direct experience with HEOS, but most reviews I've seen consider it inferior to the Wiim or Bluesound software. Try it, and if it works fine with your Tidal subscription, then leave it be. Note that Tidal also has Tidal Connect which allows you to use their app as a controller, which is usually preferred by many users over their streamer's software. I don't believe that HEOS supports Tidal Connect.

The advantage of the Wiim streamer over HEOS would be a better software suite and the ability to use Tidal Connect.

In a nutshell:

#1 A different streamer would possibly provide for a better software than HEOS to control your music access but if you are OK with it, then there is no need to change.

#2 Tidal Connect is merely being able to use Tidal, with the interface you see from your computer or mobile device, Tidal connect sounds the same as Tidal through HEOS, It's the interface that changes , the streamer and built in DAC detrmine sound quality.

#3 Roon is yet another interface. It integrates Tidal and any music files you have on a hard drive or server plus has way better functions and album/artist information but requires  separate computer or hardware to run it, and what is called an endpoint, which means a streamer that is compatible with ROON. It is also subscription based.

#4 I have no direct experience with your Marantz but the DAC has more iof an effect on the sound than the streamer until you spend the big dollars.

#5 You are not likely to hear what a better DAC and streamer will do until you upgrade your speakers so until then, Getting a Wiim streamer would only improve how you access Tidal.

With your current speakers I’d evaluate if you hear a meaningful improvement with Tidal over HEOS, and if you do just stick with that but if you don’t just drop Tidal and stick with Spotify with HEOS.  I wouldn’t bother with a separate streamer until you decide to upgrade your speakers.

I believe with HEOS you are able to access the Amazon Music Service.  I found it provided a better quality than Spotify with pretty much the same access to about any music you should choose to listen too.  I never had a HEOS so I could be mistaken but the other side is I believe that you'll get a more noticeable  change in sound with a better DAC than a different streamer.

I had a Marantz integrated amp using HEOS as well, likely the same setup you have. I did not like the HEOS app so I got an ifi streamer no dac. I used the Marantz dac. That way I was able to use Tidal Connect, and much preferred the interface.