"How would you compare them say to a Prima Luna"
Get real! It appears you’re new to tube amps?
That level of ARC and a value MIC tube amp shouldn’t be in the same sentence, with exception of equal build quality.
Both amps hooked up to same setup at low volume will sound good,and you can nit pick what the ARC does "better". Start bumping the volume-game over, ARC pulls away effortlessly.