Take it easy. I understand what you are writingI hope you have the basic understanding of electronic circuits. With output LC filter (2nd order LPF) tuned at about 50kHz/-3dB it is physically impossible to get flat FR up to 20kHz without having unstable response and low stability margin. You would need to go to much higher switching frequency and this would bring new issues. And this topology keeps FR invariant of load, so getting 20kHz flat means underdamped filter and wild overshoots in step response. Take or leave, I ask for professional discussion.
Thanks for the explanation
Some claim that you get better sound by removing the input capacitor. what is your opinion here?
I know that everything you have in the series of signal does something with the sound in one way or another
If you are interested then I have compare Naim NAP 250 clone (ljm) with hypex usd180st. hypex is much better in higher bright frequencies, frequencies where naim struggles a lot.
NAIM NAP250 amp.
(2 x 4 ohm 50hz)