Of course sound quality is very subjective. I have been into hi fi since 15 years old (now 46 ) In the main i use
active studio monitors in my main system , very accurate sound , genuinly I believe you hear the recording
if it is bad then that's what you get, when it's good then magic sometimes.
I discovered active ATC's some years ago , also use genelec monitors in other rooms
I am not saying I know good sound per say , but I do know what I like and if ATC's are accurate then I know what I like
When it comes to the X3 i really like it , but I think presently the Z2 is more accurate , if that makes sense?