Question for Amp Designers

Great question. I would like to know too.

Also lets not forget both amps are rated across the entire frequency spectrum, 20Hz-20kHz with the same THD at every frequency. So surely if the amp was tuned to sound better at certain frequencies, wouldn’t this affect the THD at these altered or accentuated frequencies to give the amp a signature sound? 

Good luck with that!!!!!

" What in the design gives these two amps the above sound signatures?"

Have you heard this for yourself or are you going by what someone else said?    

I've heard it with my own amps. I have 3 systems in my house and for some strange reason I Iike to swap out pieces to hear the changes. 

Have you heard this for yourself or are you going by what someone else said?

I think its fair to say that we hear it all the time in the world of audio. 

Someone seems to always be describing one amp as warm while another says this model is clinical.  Or its a bad fit with this speaker or that speaker because of some character that has nothing to do with the amps specs.  I remember one member on this forum constantly dissing certain brands because they were not 3 dimensional.  That seemed to be his favorite metaphor for describing an amp.  Despite specs that were better or as good as the brands he was claiming were 3 dimensional.

I think the OP raised a very intriguing question and I would like to know how these metaphoric attributes can be designed into an amp too?