Current is a component of watts (power) as Dan just indicated. Therefore, all watts are not created equal.
1 amp (of current) X 10 volts = 10 watts of power. But 10 amps X 1 volt also = 10 watts. Further, the basic W =A x V really works for direct current (DC) only. The formula is a bit more complicated for AC (as in: music signal). But leaving that aside for now, how the power is created will either be better or less good for certain kinds of speakers.
Why? Because every kind of driver generates a reactive signal BACK TO THE AMP. When the signal from the amp moves a cone back and forth, for example, the action of the cone's voicecoil in the magnetic field actually GENERATES a reverse electric current BACK to the amp! This reverse current adds to the impedance (load) the amp "sees".
What's CRITICAL (in amp selection) IMO, is HOW how that (let's call it 'phantom') impedance is created. If the amp sees a capacitive type of load (an electrostatic speaker) it needs for its available watts to consist of lots of amps (current). If it sees a resistive type load (like cones, domes, ribbons and planar magnetics) it needs for its available watts to consist of lots of volts (to overcome the reverse voltage created by those kinds of drivers.)
I'm going to generalize here, but 1 tube amplifier watt (a typical push-pull circuit with an output transformer, nothing exotic!) will be rich in the current it can make available (for that 1 watt of output.) 1 solid state amplifier watt (a typical push-pull circuit with the output transistors directly coupled to the speaker) will be rich in the voltage it can make available (for that 1 watt of output.)
You can guess where this is headed ;-) Tubes are better than silicon for capacitive loads, and silicon is beter than tubes for resistive loads. All right -- this is a sweeping generalization! HOWEVER, because the impedance of all speakers varies widely depending on frequency (the rated impedance of speakers is only a nominal figure) there could be times when you'd need a HUGE tube amp to drive those dynamic drivers (God forbid acoustic suspension woofers!) properly. Or if you are driving electrostatics (panels only, we're talking about) you might need a HUGE solid state amp to give those stats the current they need when a tube amp of far less output would sound as good (and likely better IMO ;-)
People into fine audio are generally at the 3-digit Stanford-Binet level. But many (probably most) have had little occaision to become familiar with the nature of (yikes!) circuit design. But if you will take a little time (good bathroom reading for instance as it takes several passes to sink in ;-) and go through this excellent and (reasonably) clear, easy to understand online tutorial, you will find yourself more informed than many of the self-appointed/annointed 'know-it-alls'/'experts' that haunt the halls of audio-underworld ;-)
http://www.allaboutcircuits.com/vol_1/index.html.