I use Roon and Qobuz through Roon. I could not hear a difference between Qobuz direct vs thru Roon but, TBH, didn't really attempt to compare in depth. I hear no difference between Roon playing a Qobuz hi-res album vs Roon playing the same album I own. I did compare Tidal to Qobuz and prefer Qobuz (never bought into MQA).
I can hear a slight difference between Roon and playing the same CD from my Oracle CD transport. Perhaps the transport is a bit more detailed, but it's difficult to say and certainly not enough to warranty buying more CDs.
Hey, I'm really happy with Roon (lifetimer since late 2015) and Qobuz and see no reason to change anytime soon. Roon allows me to be extremely lazy in my listening habits yet offers up a listening experience that has fundamentally changed how and how much I listen. Amazingly, my wife says so as well. All good.