I'm not sure it makes sense to me especially with the results bring to the contrary throughout all the systems I've had, own and heard.
CD has always been king by an instantly recognisable margin in quality.
The night and day difference between the older popular formats of my youth being the backend of records and main stay of tapes saw a gargantuan leap quality when the CD became the main source of the masses.
Gone were the crackles and pops of records and muffled sound of tapes ever degrading tapes.
I still bother with vinyl ans always have as djaying became a job for awhile so records were a big part of my life but the night and day difference in quality the CD offers is instant.
I stream both via a mid range pc, occasional laptop and ifizen with 2 high quality DACS on various platforms at different qualities as it brings its biggest advantage to the table which is content, content, content but irrespective it's still not as good as CD IMO.
Recently as some know I bought myself a Marantz CD 60 to replace a favourite failing but now repaired twice Marantz CD 52 mk2 which saw the dawn of streaming to the masses and I still choose to use steaming primarily as a selection process of music to then purchase the said music on CD.
Streaming was brought up at the hifi store briefly in which it was mentioned it's main attraction of being a huge library at ones fingertips but the theoretical quality is mixed bag as I've found.
It's advertised way above what you get.
I find a lot of streams of tracks bass heavy amongst other things compared to an identical track on CD with a volume difference between tracks becoming something that requires a normaliser.
I find it very similar to the days of MP3 etc in regards to what actually comes out at the other end.
One can wax lyrical about HI-Res audio, encoders, soundcards and more importantly BIT-RATE which is not unlike upgrading kit in a hifi, but I prefer the almost guaranteed quality a CD brings with it especially within the prior mentioned main decider in audio, which is it's bitrate.
CDs have a much, much higher bit-rate of 1,411 compared to streaming services like Spotify with an average MP3 bit-rate of 320kb.1 Furthermore, the fundamental audio format used by CDs establishes uncompressed CD-quality sound.
Most people think and are led to believe that some premium streaming platforms etc broadcast all the files in hi Res which is incorrect.
I often see the bitrate change on most platforms to much lower than a cd despite it being advertised as hi-res etc.
All the theory goes out of the window when I play a CD of an identical track from a stream whatever the bitrate etc, the quality is always consistently better and I've found the same throughout my hifi journey to date.
There's many advantages and disadvantages to both as said and I'm sure that claims of superiority will come from the streaming fans with huge bitrate claims and boastful quality acronyms and I'm even listening to streams now through my main hifi for convenience, but I know if and when I hit on a good track I will purchase the CD to hear it better IMO.
It's how I found a absolutely amazing band "The Lumineers" which I then bought the CD and it instantly brought their music to life.
There's a female backing singer all of a sudden ever so faintly in the background that's now added even more to an already hair raisingly good band.
I also enjoy collecting the albums knowing they can be played without any inherint problem other than clumsily scratching them.
I've found similar things when purchasing other CDs after finding something new via streaming throughout various kit.
This is all to my ears 😊 as in essence I think one should listen to whatever they enjoy however they like to enjoy it.
I say the same to people who are still in the CD Vs vinyl debate.