Don’t listen to folks who haven’t tried any given combination. I ran my ATC SCM40 V2’s with a Line Magnetic 805ia and it was bliss—sounded convincingly like ATC’s own P2 which I also owned. There are class a high current tube amps that will drive many of the 6-8 ohm speakers out there easily.
The only thing with tubes is that they tend to lead you down the high efficiency speaker path at some point. I drive my Tannoy Turnberry GR’s with a 14 watt Line Magnetic and my Pure Audio Project Duets with a 1.5 watt SET amp.