Yes, that's why I use words like "most", "almost", it is all relative. The simple fact is, heat = I^2*R so it the load is a resistor,
most of the heat involved will be in the load, not the amplifier. If the load is highly reactive, then
most of the heat will be dissipated in the output devices.
In the latter case, it is too much to try and explain it in an easily understood way as it involves more than Ohm's law lol.., so if you really want to understand the details, please do your own research as I have done in the past.
Below is a couple of places for a good start, without spending too much time on it:
Phase Angle Vs. Transistor Dissipation
And, below is interesting, but lots of people don't realize, when all they care are "power/watts":
As usual, this website covers lots more than the above on power dissipation, but the above article is just a good starting point.
Now the popular EPDR, that also seem to get misunderstood a lot, as it mislead (inadvertently) some to think high phase angle results in higher current drawn, where in fact, Stereophile use this concept to illustrate in terms of heat, the effects would be as though the load draw more current. That's a case of creating new confusion, while trying to make complex matters easier for people to understand. And specifically, in this EPDR thing, Stereophile uses the "equivalent" concept, using lowered impedance, there would result in higher current (Ohm's law) and then people can understand right away, higher current means tougher on amps, when in fact, what makes it tougher on the amp is the higher power dissipation portion in the output devices, current does not really change because if the load is say 4 ohm, if the output voltage is 40 V, then the current is still 40/4=10 A, regardless of the phase angle. It is only that with a larger phase angle, the effects of the 10 A that goes through the output device, would result in more heat in the output devices (usually power transistors) than if the phase angle is smaller. I need to stop now, as I am just writing casually/randomly, and I know I am expressing myself well, so please try the links provided and you will have better time than reading my post.
Equivalent peak dissipation resistance, EPDR | AV NIRVANA
Heavy Load: How Loudspeakers Torture Amplifiers Page 2 | Stereophile.com
