In regards to the ability to deliver current into a low impedence, that is THE weakpoint of a tube amp. Classic(not usually in the real world) solid state amps doubles power as the impedence is halved(that 200W could act like a 400W amp). A tube amp puts out the same power(unless it is an OTL, in which case it would put half as much power into half the impedence). Power ratings(the ones that we talk about) are usually specified at 8 Ohms. And with a speaker that is not a difficult load, the analogy you stated is usually accepted. But with a difficult speaker, the tube amp will never do it justice. Now, if you use one of those monsters from VTL, etc. with 16 or 32 output tubes, you can drive even a difficult speaker. But they are REALLY expensive, and get even more so when you retube(every 3500 - 5000 hours). Assuming you could buy a matched pair of 6550s(discounted, via the internet) for $60, times 16 = $960! But, if I was using a tube amp, I wouldn't not give it a difficult load. There are plenty of easy to drive speakers around today.
Tube vs Solid State - Comparable Output?
I know this is a terribly general question -- and maybe off the wall -- but is there any difference in a tube versus a solid state amplifiers' with comparable power ratings ability to generate high current? This relates to amp selection for current hungry low impedance speakers. Is 200w the same whether its created by tube or solid state? Someone recently told me that a 100w tube amp (Audio Research) was comparable to a 200w solid state amp in this regard. True or no? Thanks in advance.