First Streamer...

I think you have made a great choice. The future of high quality audio is streaming.

I have been doing digital for 40,years and only recently has it become competitive with analog and streaming can now sound better or at least as good as CDs. Also, you want Qobuz as a service. It sounds better and they have half a million high resolution albums. Better than all the rest. Might as well start there.

My rule of thumb is to spend at least as much on your streamer as your DAC, which should roughly equal your preamp and amp. Just a generality, you need to put in the effort evaluating the best and most compatible with your system. So, let’s say your

You have a good integrated amp, so $2K is the preamp, $2k amp. Your Rega is CD player / DAC… so say ~ $2K for each function. I would look for a streamer around $2K. I would look at Lumin. Assuming over time you want your system to sound better. You could later upgrade your DAC and get a performance improvement.

Alternatively, you could go Bluesound. I am not a dip your toe in kind of guy… I end up spending more money that way, but that is me. If I bought a Bluesound, it would prove to me that streaming was worth it… I would upgrade immediately (to an Aurender)… and well, I know myself, just skip the intermediate step, But lots of folks start with Bluesound.

You Can see my systems under my user ID.

I love my Project Stream Box S2 ultra

More important than a streamer is a DAC.  Even a mediocre stand alone DAC will be better than your CD player.  In the interim, you can stream with a tablet or a computer.  (Im assuming funding is keeping you from buying both, if not, then buy both).  You will see much more sound improvement with a good DAC.  The onboard DACs on CD players are not good.

And don't get a streamer/dac.  

Agree..DAC is first. I have a $15000 McIntosh integrated amplifier with DAC and phono stage. Think of this as a $6000 amp..$6000 preamp and$1500 each for phono and DAC. I purchased a $5500 DAC which was much more musical than the integrated DAC. I’ve listened to the Rega Apollo and the little Rega’s DAC sounded good for the price and I’ve never heard the Saturn.  I ripped my CDs to a NAS and used the CD player money to buy other components.

If your top line budget is $2k then @ghdprentice gave solid advice. If I were in your shoes I would consider the Bluesound feeding your Rega and save the rest for when its time to upgrade. Bluesound seems to be the gateway drug to streaming although I have never used one.

@carlsbad is mostly right when advising against a streamer/dac but ONLY in the context of your budget. There are exceptional streamer/dacs that aren’t in your price range presently (DCS, Bricasti, Meitner, Totaldac, MSB, etc). Another option would be to stretch your budget into the $4-5k range and consider a product like the well reviewed Hifi Rose RS150b. It would serve as your hub and integrate everything analog or digital as well as any a/v needs.