Tube Power vs Solid State Power


I continually hear Tube power is more powerful than Solid State Power. IE; “A 20 watt tube amp’s power is like a 60 watt Solid State Amp’s Power” and so on… Is this true ???

I always think of the “What’s Heavier, a pound of Feathers or pound of Rocks story?” A pound is a pound right ? 
Maybe someone could offer some thoughts and explain if this is true or not. 
Thanks
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All I can say is what I’ve experienced. I have 95 db sensitive open baffle speakers from Spatial. I’ve run about five amps from six watts a channel tube up to 700 watts a channel solid state mono blocks. Of everything I tried, 20 watts of transformerless tube has the best bass, best dimensionality, best imaging, best everything. More watts didn’t make for better sound, just more headroom I didn’t need. 
The tubes I’ve had sound way fuller at low volumes therefore sounding more fullfilling at low volumes. If you really want to rock out at 100db levels I think you need some watts and some current. I’ve not had high dollar tubes but that is my experience. If I liked 80db or under it would be tubes all day especially if it was not too busy music. 
Ohh the one I had that demanded tubes was Klipsch Chorus 2s. They rocked like a mutha but still needed some eq to tame them. The Tekton DIs I had sounded really very awesome with the Cayin A100 I had but only till about 80-85 db then they sounded a mess. 
I’ve now owned a few SS amps and a few tube amps…. Mind you, I now own a really hi-end tube pre-amp and power amp set and I’m loving the tube sound…

I compared the $35k Gryphon to the $20k ARC and my ear goes to the ARC amp every time… 

you listen and learn… no right answer…right boys…?