Streamer/server newbie

For $5K you could build a nice Roon server and endpoint.

Look at an Innuos Zenith.  It’s got an onboard CD drive and storage, and their Sense software is free and gets great reviews for both usability and sound quality and is constantly being upgraded.  They offer great customer support, and you can add their Phoenix to gain further improvements.  You could also look at Wolf that also gets great reviews and may be in the same price range.  Best of luck. 

Intel NUC Roon Server is around $600.

A Raspberry Pi 4 with Ropiee is about $250 + linear power supply $90.

Roon lifetime subscription $830.

Spend the rest on a good DAC, amp, speakers, headphones if any of those items you already have are something you might consider upgrading.

I have the above setup in one system and I also have a Lumin U1 streamer in my main system. The upgrades to DAC amp and speakers are so much more bang for the buck then the small improvement in sound by spending $5k more on U1 streamer...don’t get me wrong it is a great streamer but it was the last component I upgraded. I was shocked and surprised at how good the Raspberry Pi sounds into a good DAC (USB connection - no hat). Everything I read and see online says buy a streamer costing thousands.

You have a healthy budget but that doesn’t mean you are required to use it.  Since you aren’t that sure about streaming I would suggest go slow.  The largest determinant of sound is the DAC, and you have one that you like.  Transports matter, and the more that you spend, the better you get, but affordable streamers

such as Bluesound sound pretty good, especially with High Resolution material.

My suggestion is buy a less expensive but quality component.  If you later decide streaming isn’t for you, you won’t be looking at a $5K albatross on your equipment rack.  If you love streaming and down the road wish to upgrade, then spend more.

Streaming frequently isn’t plug and play like.CD player or even a turntable.  They are more like networking computers and subject to the same foibles.  For example, the software program is a huge part of the experience.  I had a Bryston streamer that sounded fantastic but was hugely frustrating due to a horrible software program.  I replaced it with a Cambridge Audio CXN 60 that cost 1/3 as much, sounds about 96% as good, and has an easily managed app.  It also has Chromecast and AirPlay so I can stream directly from a mobile device if I don’t want to play the files on my server

Lumin U2 or U2-Mini are great choices.  (I'm a Lumin dealer)

But you mentioned "download"....neither of these will have on-board storage, so if you truly want to download cds, you will need a NAS or storage device.  If you only want to stream (Tidal/Qobuz/etc), then you are good to go.