Decent DAC/Streamer

Mahler123 The Node 2i has a 3.5 MM toslink optical digital input to allow it to accept a digital source. It even comes with an adapter to convert from toslink to 3.5mm optical. I run an ancient California Audio Delta transport into one of mine.

The apple tv is not known for sq. Start there.

Interesting I thought the toslink on the Node 2 was an out (that is how I use it) but it can also be an input?

You need the mini optical adapter (comes with node accessories) then the 3.5 mm input on the back becomes a digital input.

My node2i has one mini optical in. I wish people wouldn’t make repeated assertions about equipment they don’t use....

To OP, I can relate to your budget limitations. 

Although the node 2 was easy to use, it got some bad reviews for its sound quality.  The dac in the $500 2i is improved from that in the node 2 it replaced. It’s not the best dac ive heard (for $300 or $400 you can now get a fantastic sounding outboard dac that will convert even MQA) but to my ear it sounds better on its own than when I played it through my Schiit Modi (they call their newest Modi just a Modi, not modi 3) which is supposed to be better than the Modi 2 Uber (but I never had one).  That is not saying much though.  I’m not very impressed with the modi.  I have two different inexpensive wi-fi devices with internal DACs that sound far better than the Modi: One is an old Gramofon that I got on eBay for 20 bucks.  The Gramofon plays Spotify connect as good as $1000 DACs I’ve heard converting sonos.  The Gramofon does not however play airplay. (The Airplay aspect of Apple TV use is another story and is also part of your current sound quality problem).  The other is this inexpensive Klipsch WiFi bridge gizmo:

Klipsch 1063275 Gate Playfi Gateway Wireless Multi–Room Hub

https://www.amazon.com/dp/B01M5B793S/ref=cm_sw_r_cp_api_i_ITFFCbA4Y015E

This thing is like an Apple airport express (not a router) but designed specifically for audio.   It sounds way better than Apple TV - which I regrettably used for years hooked straight into the optical port of my amp, not through the tv.  I also tried Apple airport express, which was a slight improvement over Apple TV but still pretty bad, and Chromecast.  (Chromecast audio puck is a non-starter, i tried one and I agree it sounds wretched and cannot be fixed by a dac or reclocker - I tried).  Anyway, the SQ from the Klipsch is a little different but about as good (I think) as from my node2i.  I feel sort of foolish saying this but the $35 gizmo sounds as good as the $500 toy.  Others agree.  I will add that I have played amazon music through my node 2i and it worked fine but have not tried it with the Klipsch gizmo.  It’s playfi so I’m assuming it works. 

Something to think about might be what you’re going to use the set up for.  If you’re not playing a lot of your own files off your computer or network drive (which the node does quite nicely) and just using service(s) you can improve SQ pretty inexpensively.  My view, and YMMV, you have to spend more than a grand on a good WiFi/streamer/server/dac setup to get significant improvement in SQ over one of the above <$40 approaches.