How do amplifiers work?

It's unfortunate that magazines like Audio, or Stereo Review or High Fidelity no longer exist. In the "good ol' days" they usually ran an article on basics once a year, maybe more. In those days, we simpletons believed that there was some science behind audio that was worth knowing and considering. Then came TAS, Stereophile and the others who started spitting in the soup and telling all that whatever could be measured meant nothing. So now we have a new generation of people interested in hi-fi that cannot readily find such material. I encourage you to find out about these questions and do believe that there is one book out there that presents it cogently; if I could only remember the title. I am sure others will be able to provide it to you. The one thing that I remember is that unlike, let's say a milk bottle that can only give you its maximum quantity, an amp is not like that since it will try to put out more power than its rating when the load demands it, only with a great amount of distortion. One magazine said that it is like if instead of the milk bottle running out of milk, it started providing sour mil instead. There are many factors to consider and some others here are better equipped to explain. There used to be Sean, but he was run out of 'Agon Town on a rail for some reason that may forever remain a mystery...

Yes, an amp does have peak power normally quite a bit in excess of its nominal continuous rating. The class in which the amp works, the size of its power supply and whether it is stiffly regulated or not are all factors in by how much an amp will exceed its average rated power on peaks. Interestingly enough, in the days when objective measurements were not met with some kind of exorcism rite there was a spec often provided as to the “dynamic headroom” of the amp given in dBs. High Fidelity magazine also touted rating power amps in dB watts so that the single number given would correlate better with the ability of the amp to actually produce an increase in SPLs. The single most significant number that would address your concerns though is the dynamic headroom figure. Dynamic headroom probably accounts in great measure for this subjective audio notion that, based on listening to different power amps (ostensibly in the same system and the same room, but subjective audiophiles are not prone to quibbling over mere details such as limiting the number of variables), you get your "bigger watts" and you get your "smaller watts", then you can also get your "tube watts" and your “solid state watts". All this constitutes, in all likelihood, more bogus observations from the subjective front. It can all be explained "scientifically" and far better than by a duffer like me. Good day.

The weight of the amp is some kind of indication of its prowess if you are talking about class A or AB amps. Those with switching power supplies can be made to be very potent and still weigh very little (ask Bob Carver). How they might sound is another issue almost entirely (don't ask Bob Carver). Again, toroidal transformers, I think, usually weigh less than standard ones for the same rating, so that the weight thing is at best a rule of thumb of sorts. Subjective evaluations are all very well and good (in fact they are neither, but that is too contentious an issue to deal with here), but don't expect a proverbial quart out of a pint pot. BTW when you are driving along in your car when you want to gauge how fast you are going don't look at the speedometer, judge it by the seat of your pants. As in subjective audio, if it feels fast, then it is fast. Think about it as subjective autophilia...