Question/Help Needed: Boomer who is totally inexperienced with DACs and streamers.

WiiM Pro Plus.  Very good reviews and inexpensive. 

There are many options as you can see.
IMO, for someone just starting out Bluesound Node is your best bet. They’re easy to use, have been around for a while and support a wide variety of streaming services, including Amazon. Use USB to connect to your dac and you’re good to go.

Another boomer here who also recently got into audio streaming. I went with the Cambridge Audio CXN-V2 network streamer for the simple reason that most of the reviewers stated that it was an excellent first unit with surprisingly good sound. I will vouch for both. It has an internal DAC with analog outputs, and also digital outs for use with an external DAC. I have been using the internal DAC and have no complaints with the sound. It was easy to set up, and Cambridge's StreamMagic operating system makes using the available streaming services very easy. I have been using it on a trial with Qobuz and have been very happy with it's performance, along with Qobuz's selection and Hi Res offerings. It has a nice full color display that shows the album cover and other pertinent information about the track playing, and putting the StreamMagic app on your smart phone gives you full control as well. It also comes with a full featured remote, but I prefer to use my smart phone. A pleasant surprise is that the CXN-V2 also recognizes my Sony HAP-Z1ES server as a music source since it is on the same network. I run both units on an ethernet connection rather than WiFi.

+1, @arafiq on Node. 

Boomer here also.  Using your Alexa to stream will give you a very compromised sound quality.  The Alexa receives the streaming files via MP3 protocol,  which is a very lossy compression codec. As suggested by several previous posters,  I  would recommend either the Wiim Pro Plus, or the Bluesound Node, and take the digital output into your DAC. I have a Bluesound Node and use both Amazon and Idagio for streaming services. The Node supports Amazon streaming in Ultra HD  (24/192). I'm not sure what the Wiim supports. You won't have voice control,  but the Bluesound app control from a phone or tablet is very intuitive and user friendly.  I  have a very resolving system,  but have stuck with the Node just because of the app and the streaming services that it supports.  I did modify the Node with a TeddyPardo Linear Power Supply, which really improved the SQ.  I now use streaming for about 90% of my listening. Good luck with your audio experience!!