tube watts vs transistor watts?

Even a solid state amp that claims 200 watts of power does not make it a certainty that if impedance drops below 4 ohms and closer to 3 will it do the job without current. High, stable current with lots of reserve at the ready. Without it watts mean little in either camp. IMHO.
Cheers

There's lots of informative answers here but I'm not sure they have answered the original question.

When an SS amp approaches its power rating, it will go into distortion very, very quickly. Suppose it is rated at 200 watts; then if you try to get 210 watts out of it, you could easily get 10% THD or more. It will sound totally horrible. So in practice, you would not actually want to go anywhere near 200 watts with such an amp, because the power level of a music signal varies greatly and you are just asking for trouble.

On the other hand, the tube amp rated at those same 200 watts (this would be a little beast btw) can go to 210 watts and the THD might not go a whole lot higher than 1%.

So it's not so much that the tube amp is more powerful than its rating, but rather that the SS amp is not as powerful as its rating (by comparison); that's how I think of it.

That, and the realization that 30 watts is a whole lot louder than we think. :)

That is not correct, it depends on the amplifier. My Musical Fidelity NuVista M3 is rated 275 at 8 ohms, my tech friend measured 325 with extremely low distortion. It will pulse over 800 watts at 2 ohms. Any good amp will deliver much more than its rated power for very short bursts, that was the basis of the late , unlamented "peak" power or "music" power ratings. Any amp that behaves as you describe is a bad amp and should be avoided.

One thing that tube amplifiers/preamplifiers do so well that solid state amplifiers do not is reproduce those wonderful micro dynamics. Those subtle nuances. So when listening to tubes you are not looking so much at the big dynamics like drum beats etc but rather to the subtle musical characteristics and so you don't feel the need to turn up the volume as much, you hear more at lesser volume.

So perhaps not so much about power as about perception.