How good is Blue Sound Node 2 in WiFi vs Ethernet connection vs external CD player?

I have the Node 2 and play Tidal via WiFi.  I connect it to the DAC in my Esoteric K-05 SACD player and it sounds very good but not as good as a cd.  I haven't tried it with an ethernet cable.

I think the answer to your question will depend on quality of the CDP you use as a transport. If you are just trying to compare the differences in sound quality between a WiFi connection vs. a hardwired RJ45 with all else being equal, I don't think the differences will be significant assuming you have high speed broadband internet access and your router is not too far from your Node 2. Needless to say, hardwired connection is immune from occasional loss of reception between the streamer and the router. Curious to hear if others have noticed a difference between the two connection methods.

I find myself not understanding the OP.  The Node 2 has a built in DAC.  It's ok but nothing special.  If the Node is connected to your pre amp by the analog connects that is the DAC that you will hear.  If you connect it digitally to an an external DAC then the external DAC will be heard.  Which is better?  Devil is in the details.  If you have a stupendous external DAC, I would respectfully suggest using it.  If Said external DAC is a $39 Wal-Mart special, use the Node.  When in doubt, listen yourself and see which you prefer.
   Wired vs Wi Fi?  The manufacturer suggests wired.  That's what I use.  My wi Fi set up is somewhat dodgy, thanks to the incompetent folks at AT&T.