Everyone has offered valid points. Perhaps the only thing I can add are some real world examples. In my experience(especially within a manufacturer's line), the smaller, less expensive amps are faster. The bigger ones are stronger. If you have demanding loudspeakers, requiring the power, you need the larger amps. But if you speakers are more amplifier friendly, the smaller amps can give you more musicality(I know I am going to be ripped by some for saying this). In my opinion, it is related to the power supplies. Massive transformers, and coffee can sized caps make a lot of juice available. But it is often slow and unweildy. An analogy would be comparing a dump truck to a Toyota MR2. The dump truck has the torque, but is slow and ponderous. The MR2 doesn't have the power of the dump truck, but is zippy, light on its feet, agile, and FAST. I think that the easiest place to find these differences in audio amps is to compare North American and European amps. Euro amps are smaller, lower powered, and faster. Examples would be Musical Fidelity, Electrocompaniet(not all of them), Jadis, Kora, Audio Analogue, LFD, Cambridge, Pathos, etc. American/Canadian amps are bigger, more powerful, and slower. These brands would be Krell, Mark Levinson, Jeff Rowland, Classe, Bryston, Audio Research, VTL, etc. For Thiels, you need the current of the larger amps. For Triangles, you can use the smaller amps. I have been through a complete metamorphosis over the past decade. I used to be on one side(big amps), now I am on the other.