Ableza
Headphoneus Supremus
The day 6 Moons becomes a reliable source for technical information is the day I eat my hat and resign from all things audio.read this review ,an amp tested with a lot different speakers have different result...
https://www.6moons.com/audioreviews2/firstwatt2/1.html
Rather than get into a discussion of DF and its importance (or lack thereof) to audio amplifier performance, I will bow out of this discussion by referring you to a more technical resource, although one still written in layman's language: https://trueaudio.com/post_013.htm Perhaps this will help you, perhaps not.