Tube Amps Watts vs SS amp


Can someone explain is there is a difference between the watts of a tube amp vs vSS amp, Looking to get a tube amp ,but i see that the watts are much less than the SS amps, So how do these Tubes amps with 25 -70 - wpc drive these high end speakers, I have a vintage pair of AR 9s and 2 mcintosh MC2200 amps in mono (400 WPC) to drive these ,what tube amp will power these under 3-4k new or used, Thanks 
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Frankly I would change you speakers to more efficient speakers. You might be amazed by the quality of modern speakers. Also the posting on the liveliness 
of tube amps is right on the mark. No solid state amp can equal the sound of tubes, that is the presence, sound layering and ability sound good at low volume levels.
@mijostyn : The Heresy's date from 1957 (same as Quad's). I think they sound even better with my First Watt F5 (25wpc). Still, for dinosaurs they are certainly capable of rocking out - try a nice vinyl copy of the Stones Let It Bleed!
@browndt: "No solid state amp can equal the sound of tubes ..." NONSENSE! I'm sure that Nelson Pass would agree with me that either type of device is capable of accurate reproduction of a musical waveform! 
A pair of those big 600 watt ARC mono amps would be great with the AR9's - but at what cost!