To Stream ...

Here's what I've got:
PS Audio PerfectWave transport
Chord 2Qute DAC
Modwright SWL 9.0SE Preamp
Butler 2250 Amp
Modified Maggies (by Peter Gunn)

What I'd like to do is stream from a service such as Spotify.
--I mention Spotify as I currently use them to stream music to my iphone when I'm out and about and I've just heard they will soon be streaming in lossless.
I know little about streaming and after reading through a few threads, don't feel like I know much more about it.  I hope this isn't a sign of my older brain.
I currently receive quite fast internet service via a cable modem and then a router that provides ethernet cables that run to various rooms in my house.

The question: What do I need to buy that will plug into one of those ethernet cables and take the streaming Spotify data and feed it to my preamp?
Is there such a thing?

And let me state now, I understand the audio quality will be less than what I'm currently used to but that will be OK for the amount of time/type of listening that will occur while streaming.
And the emphasis here is simplicity: one device that does this, not a bunch of things with a bunch of connectors ....or building something myself (not doable).
Is there anything out there that fits this description or is my question semi-nonsensical and reflect my inadequate understanding of the concept of streaming?
Spotify uses their own Spotify Connect wifi solution and to use it you'll need a device like the Chromecast Audio. The Chromecast Audio device has optical out which will connect nicely with your DAC. Bluetooth is another option as well and of course you would need a Bluetooth receiver type gizmo (I use a Wyred 4 Sound bLINK). I'm sure their are other examples. Best.
Hello Andrew -
Listening to Spotify as I write. Can’t help you with an ethernet path (I don’t think). For a long time I’d been running Spotify into my main system DAC via USB cable out from a MacBook Air; from the DAC into my preamp or integrated amp.

More recently I was able to get the MacBook and long USB cable out of the path. I got an Aries Mini (~$500). It does Airplay. I have an Airport Express wireless router in the house connected via ethernet to my Comcast/Xfinity modem. The Aries DS Lightning software residing on my iPhone sees the Airport Express and the Mini. I fire up Spotify on the phone, choose "other devices" (or something like that) from the bottom of the phone’s screen and then pick the Aries. Spotify streams off the internet via cable to the wireless router to my phone and then to the Aries Mini - at least that’s how I think it works. Regardless, it sounds great and I am no IT genius. Good luck. Don’t get discouraged. I think streaming is the way to go. By the way, you have some nice gear in that system.
I run my Macbook Pro directly into my Devialet. I use Tidal though. It has better sound quality. When Spotify goes lossless i will look at that. Tidal has most everything though. I have a couple thousand LPs and maybe 8 thousand cds and streaming seems to have made me look like a fool for having all that stuff. 

Just to clarify my comments...
The Aries Mini can run Tidal as well as Spotify (along with a number of other "sources").   While Tidal's content is growing, at least in terms of music I like, I still find myself quite frequently resorting to Spotify because Tidal just doesn't have the stuff; latest example, most of Arbouretum's catalog.