OK, so If I can use the HD4 with TIDAL, how come you're not listed on TIDALs website?

The devices on TIDAL’s website are network media servers with the TIDAL app already  on their operating systems. That’s all. Thankfully, there is no difference in audio quality or anything else as compared to their downloadable app. The only difference is just that TIDAL comes pre-installed on those devices. There is one notable exception, though: If you're listening to TIDAL on a computer, then Google Chrome is the only web browser that supports its full audio quality.