Are tube watts equal to solid state watts?


I remembered reading sometime back that the power for a tube amp is equivalent to double that in a solid state amp. So for eg. a tube amp with 40watts is equal in power to a solid state amp of 80watts.

Did I remember reading that correctly?

Thanks
hlgoh2006
I have to add this to the discussion.A while back I run with success,my Aerial 10T,known to be power hungry speakers with a Conrad Johnson MV-55.
George
A watt is a watt is a watt. Only present day audiophiles would ask this question. Making a distinction without a difference is the territory of subjective audiophiles, but hey these days anything goes!
Agree that the subjective appearance of 'more power' from a tube amp is due to the fact of "soft clipping" (the amplifier when pushed to the limit of maximum power distorts in a friendly way) vs the solid state amp's tendency to sound dreadful when pushed to the limits and it begins to 'clip' the signal off.
Solid state amps could be designed to sound like the tube amp if the manufacture wanted to do so. (but the tradeoffs in non-clipping situations causes most if not all to avoid this.)
Regarding the demonstration of the 30 watt vs the 200 watt amps above, perhaps there's an explanation that would explain the apparent lack of difference.

As a youngster, I remember most of the receivers I owned had power meters (you all remember the 70s, right?). I recall watcthing those meters rarely getting above a couple of watts.

It seems that the speakers would have a tremendous impact on the demo. If the speaker were relatively efficient then they should be able to produce high SPLs using either amp because at no point was either amp pushed to its limits.

If my supposition is correct, then it would be hard to perceive a power differential. I.E., regardless of total capability, consuming a couple of watts from either amp isn't operating at the limits.

The other point I'll offer is that the difference between 30 watts and 200 watts isn't that great. If a doubling of power is required for a perceived difference in loudness (I think that's 3 dB, but could be wrong), then the difference from 30 watts to 200 is around 6-9 dB (I could be way out of my depth here, so please correct my thinking if it's wrong).