I listened to the Focal Micro Utopias through a Cary CDP coupled to a solid state BAT pre amp and a solid state amp that was switched 20 minutes later, to tube amp.
I immediately prefered the sound of the tube amp and my preference remained after a switch back to the solid state amp.
The first amp was a $4000 solid state amp, the second was a $4000 tube amp.
I was previously, generally biased against tube amps based on personal, negative, experiences with a tube amp and preamp combo I had in the 80's.
I'm still not sure I would own a tube amp, but I can tell you I preffered the sound from it in this otherwise all solid state system. The difference was easy to spot through the Micro Utopias.
In high end audio, tubes are everywhere. Apparently, for good reason.