Flat/transparent amplifier but not speakers/IEMS/headphones

[Zensō]

TBH my take was that as soon as an amplifier/DAC/tubes colour the sound it's bad yet when speakers/headphones/IEM do it they are not down marked for it...

I don’t believe that’s true . The most highly rated speakers here almost always have close to an anechoically flat response (downward sloping in-room).

As for headphones, to sound neutral (similar to a flat speaker as above) their response needs to approximate one of the standard curves (DF, Harman, et al) to compensate for the HRTF.

 

[Haider]

Thanks for the explanation