I am unsure what that really means. As far as I know, there isn't an analogy between "grunt" in amplifiers and torque in motors or engines....in that diesel engines can have massive torque compared to a gasoline engine of similar displacement, but don't run at high rpm, so they are said to have "grunt" but not (horse)power.
Is there such a thing as a "non-beefy" amp that can deliver power????
If P = V * I, and V = I * R, then P = I^2 * R, correct? For a fixed impedance, that means the peak power an amp can deliver is directly dependent on the ability of the amp to deliver current.
Someone please disabuse me of my ignorance, if that's the case.
I didn't see a clear response to your question, so I'll take a stab.
I believe "grunt" would translate to how "responsive" the power supply is - i.e., it can deliver the needed amps very quickly.
A "beefy" amp would have a large chunk of iron that would hold (or store) a large amount of energy in the magnetic field. When you have a need for a lot of amps (e.g., sudden, large change in volume) or very fast changes in amp draw (e.g., plucking a string), having the ability to pull the energy from that stored magnetic energy helps a lot versus going all the way back to the outlet to get the needed, rapid change in those amps.
So, all else being equal, a low cost "non-beefy" amp would
not deliver the same performance as a "beefy" amp for music with large volume changes or which presents lots of detail.
Put another way, if you played a 1000 hertz sine wave through a "beefy" and a "non-beefy" amp at a continuous volume they may sound the same ( all else being equal, including the power rating). They would not sound the same when you start changing those sine waves in the form of classical music or action movies.
BTW - this is my first post here. While I'm an electrical engineer, I'm not claiming any expertise whatsoever in the audio engineering field. I'm sure this response will be critiqued, corrected and/or modified by others.
Also, as a new member, I sincerely appreciate this forum as it is very useful and informative. I do find it interesting that for a forum that uses the word "science" in its name, terms like "grunt" and "beefy" are used when trying to explain techncial concepts