How do tube Watts compare to SS Watts?


I have Theil 2.2 speakers, which have a low sensitivity (86dB), but I would like to get an intergrated tube amp. Or even all tube. But I don't know how many tube Watts I'll need to drive the Theils. My guesstimate is @ 50wpc for intergrated tube amps, but that could be wildly off. Are their mathematical conversion formulas? Second, if there is a rough range, might you be kind enough to suggest a few worthy candidates that, wheather new or pre-listened, are under $1,000 USD (e.g., Cayin model xxx). Thank you most kindly.
rascal52240
>>whereas ss amps, is "what you see is what you get" Not much can be done for a ss amp. Its all "hard wires"<<

I think Nelson Pass, Hervé Delétraz, Charles Hansen, etc. etc. have proven that is quite untrue.

Thank you.
rascal, listen well to unsound advice. he has firsthand knowledge and based on my exp with jolida 60 wpc and$$$ he is right on the mark. a watt is a watt basically. thiels need POWER! an old tube amp is no more powerful than a new used tube amp. shop around awhile if you can but 60 wpc in a tube is not more than 60 watts from ss even if the ss has a rolled off clipping circuit like NAD offers. unsound has spoken with thiel himself and is really doing you a great service. 60 wpc may sound good but 100 is going to make them sound as good as they should. fwiw, in your $$$ range the sonic differences between tube amps is not as imp. as wpc in the case of driving low eff. speakers. ;)
Bartokfan, the assumptions you make pertaining to the characteristics of tube are incorrect. There are a great deal of variance is sound characteristics of any given tube from different manufacturers. A Tungsol 6550 sound very different to an Electra Harmonic 6550, which in turn sound different to SED, Svetlana or Phillips 6550s.

Additionally, factors such as the circuit design, quality of components, screen grid bias method etc. etc. have dramatic effect on the sound.

EL34 are generally known to be very melodic when run in triode mode, yet partnered with the right speakers they produces a prodigious bass slam in my V12i. KT88’s are known to have bass slam, but they are wonderfully melodic and detailed in my Audionote.

Observations on what a amplifier/tube sounds like, should be made after auditioning, not before.

Regards
Paul