Hype aside like all things in life also for audiophiles there's no one size fits all all the time solution but this is a good reference amplifier and achieves low thd in a sober manner. The room, speaker, amplifier and music interact in complex ways and the ear and brain decide what it wants to hear. The brain is a great dsp if a certain threshold is met
The Pathos here sounds really good even on YouTube music. It is not a slop when it comes to bass performance signifying it is heavily biased into class A. How does this no feedback design sound so good? Why aren't THD values solely winning the day? It may all boil down to stability. Also heavy class A is warm in nature. Couple that to the characteristics of tubes and you have a winner. Also BJTs can have a more pleasant sound when used in the output stage, but how is the Pathos getting away with mosfets? Pathos takes advantage of tubes to full advantage by going for full voltage gain immediately the voltage gets into the amplifier, this alters the signature of the incoming signal, feeding this through a bjt stage would be a tad bit too much, so mosfet characteristics are used to further modify the output signal. This combination gives authority to the tube distorted signal which comes in as enticing and warm to the listener rather than cold clinical and snappy. Back emf has nothing on the heavily biased zero feedback class A output stage. This combination makes the mids sound the best and doesn't cause ear fatigue. So far designs such as SYMEF here and 1DIFFQC here as well as most of our designs have aimed at a pleasant presentation, especially people have found SYMEF to be enticing and have even called it a tube amplifier. These two amplifiers also are no slops when it comes to bass performance. Some SYMEF owners found the vocal presentation enticingly real. With a powerful low end, beautiful vocal presentation and not in your face high end these are the characteristics of a very good amplifier. The newer ultralow THD 1DIFFQC designs are gunning for that lower THD and with it comes inherent risks including change in sonic character which hopefully have been adequately addressed. So while the 1DIFFET is imposing on first glance, a lot of factors dictate the success and application of any design. First off you probably want to use the design for low end extension where the unforgiving nature of mosfets can tackle those problematic room modes or it might even surprise you and you may like it a lot for full range reproduction or you may simply find that you prefer the SYMEF or 1DIFFQC for whatever reason.
You can also play with this wonderful design with an nicely small PCB design https://www.diyaudio.com/community/threads/2diffet-amplifier.239753/post-7174549