The implied prerequisites are a decently fast and reliable WiFi network in your house that is connected to the Internet at a decent rate and a computer or smart phone also on your WiFi for control.
With that, to start streaming you need a network streamer, a DAC and a streaming service subscription.
The Network streamer is a hardware box that connects to your WiFi to access the streaming service via the internet and it provides as output a digital signal (optical, coax or USB) that you connect to the DAC.
The DAC converts that digital signal to analog stereo that you connect to your pre-amp via normal RCA interconnects.
Free streaming services are available although I think those are provided at lower bit rates (less or far less than CD quality) and may include commercials. For high-quality sound as appropriate from Mc gear, a high res streaming service should be used. I prefer Qobuz as their library is all at CD quality or better but you can shop around.
The network streaming and DAC hardware can be done in a bunch of different ways some of which are listed in the posts above. Your smart phone or computer can do both functions with various levels of quality but separate units as listed above will likely give better results. Given good WiFi (or Ethernet) connections, I suspect the quality of the DAC is the most important item for setting streaming sound quality (but not sure there is universal consensus on that).
If you meet the prerequisites, I also recommend the Blue Node as a starting point. It is one hardware box with both a network streamer and a DAC. It has connections to use it as a stand-alone streamer used with a different DAC (e.g. post #8 above) if you already have a DAC or wish in the future to upgrade to a DAC external to the Blue Node.
To use the Blue Node you need to download the free BluOS control software (also used by NAD streamers) to your smart phone (or computer or both). Then plug the stereo audio outputs to your preamp and run the control app to get started and control the music.
You'll need to go to the website of the streaming service(s) you choose to set up the subscription and an account (could be more than one). You can then go to the BluOS app and set up to stream from those services using the account information. Then your going.
I like the Blue Node because it is relatively inexpensive, provides all the necessary functions, runs BluOS software which relatively well written and supported (i.e. by NAD and Blue Sound) and easy to use, can also be used with Roon software ("Roon Ready"), can be used with a "better" external DAC as an upgrade, and can be resold relatively easily. (In your situation, I would not worry about Roon but it is good to know that your network streamer will support Roon should you go that way in the future.)
I have not tried other hardware approaches (like some listed above) so cannot comment on them relative to Blue Node.
The MB50 looks to be a similar product to the Blue Nude but runs the Play-Fi software. I don't know how that compares to BluOS nor how the sound quality compares. (I use Roon which does not appear to be supported by the MB50, so that's a show-stopper for me.)
Note that neither the Blue Node nor the MB50 have digital USB outputs for use with a USB DAC.
Any corrections or clarifications are welcome.