op
two points to raise in reply to your op above, in the spirit of discussion...
1. achieving a flat, in phase response, at the prime listening position in a room/system setup is a laudable goal, if for no other reason than for the listener to judge/realize that some deviation from this ideal may make the music as presented seem more ’beautiful’ or ’real’ subjectively -- i have not tried to dabble in this pursuit myself, but at least regarding frequency response, this is what a lot of the room correction tech in modern gear attempts to enable
2. on a subjective basis, when it comes to voicing of hifi components (and most prominently speakers), there is some agreement that numerous successful but aging designers are releasing newer products that have greater/too much treble energy (as they personally are experiencing a reduction in their ability to hear higher and mid treble frequencies, but have yet to admit that, and still insist on personally voicing their gear) -- folks such as richard vandersteen, mike/jason at schiit, frank van alstine, and david belles have all been ’accused’ of this...