Everything else being equal, should I expect better Spotify quality through wifi or USB?

kijanki.  Great information.  Thank you.  Is there an easy way to tell what band my wifi is operating on?

I use dual band router and dual band receiver (Airport Express).  My router has different IDs for different bands.  On my computer I select one corresponding to 5GHz (can be checked in router setup).  It also depends what do you use as receiver.  Many products, like Airport Express, don't allow direct connection (ad hock) and require router, while others might work direct.

gasbose.  I am still a newbee, but I believe I would be correct to say that you cannot expect great performance from a $25 DAC from Amazon.  I just tried a Google Chromecast audio "puck" ($35) into my receiver via the analog output, and I was not impressed at all.

I just bought a used Cambridge Audio 2 channel amp, and am thinking of getting a Bluesound Node 2 for the streaming and DAC functions.  I listened to one at a store, and it was decent.  I also listened to a $4K Linn DAC, and at least for Spotify, could not really hear much difference when compared to the $500 Node 2.  I am going to try using some old Klipsch KG4 speakers I've had in storage for 10+ years.

What you deliver, by Ethernet, USB, Wi-Fi is just data. The question is how this data gets to DAC. My Wi-Fi receiver has analog and digital (Toslink) outputs. Digital could be better (280ps jitter), but fortunately my DAC has good jitter suppression, but analog (that I don’t use) is horrible (according to Stereophile) showing artifacts of around 1000ps jitter. If you cannot get data to DAC directly be sure that receiver/converter doesn’t add jitter. Many people go USB to USB/Spdif converter. Timing is not important with asynchronous USB but is important with Spdif (real time clock). If this timing is shaky you need reclocker.