Thing is, my experience is that alot of the sought-after gear and effects ARE very subtle in their differences, and it's more of a sum of all the parts (tracks? :O) ) that seem to do the thing. You read these interviews with some big producers and they get into this high-end AD converter over that high-end AD - jeez, anyone ever did THAT comparison? You're talking splitting hairs..
But when you get rid of all obvious problems such as bad cables, cheap mics etc etc, I suppose the next level is to address all the details.. A friend of mine mixed some stuff at British Grove (Mark Knopfler's place) with Mick Glossop about three years ago. At that time, they were throwing out their old ADC's in favour of Prism (not the cheapie Orpheus either) - at a HUGE expense. Does anyone else care, or hear the difference, or pay more because of it? It becomes an academic game for the geeks, in my opinion. And bless the geeks - they are the technical pioneers.
But anyone can hear a good song over a bad one :O)
L.