Not sure how Phonitor got on this list from us, to my knowledge none of their products are a good fit. When you look at their power and distortion curves it's quite clear they optimized for 150 ohm dyanmic headphones. I spoke with one of their engineers who confirmed this.
We also stopped recommending the AK. We dug in and ohms law does not apply, the unit severely current starves into low Z loads. AK does not seem to like posting actually power at different loads, just the voltage they swing, which is only relevant to high Z loads that don't pull current. The rest is right as those vendors have strong current capacity.
We have plenty of other gear on the list these days, though not a ton of new portable options we suggest.
Power is a complex question, for sure. We generally put out a number that will get to the point of being too loud to listen safely for a long time, e.g. > 100dB.
I myself have a couple of devices, like a WiiM Pro as my bedside unit. It only has something like 150mW
@32ohms yet puts out quite solid bass and plays as loud as I listen to, even on a Stealth.
We generally rate a bit higher on power than I listen to give the average user headroom to get louder without clipping, as nothing makes for a bad experience like clipping. That said, YMMV. For example someone turning up bass EQ will want more power to bump their EDM at moderate midrange SPL, while those listening mostly to acoustic will likely never come close to the min recommended power except perhaps a crescendo in a symphony.
The one thing I've learned is that there will always be someone who listens way louder than safety dictates, and for them more power is needed. For most other people are min should be fine.
As a last comment, it's not been our experience that having excess power translates to better sound, but having too little does, if you are hitting clipping or are getting current starved. For those reasons I suspect some people will always want more than the minimum.
