Harry Pearson started the obsession with the "soundstage" in his first issues of TAS. Gordon Holt’s first concern was with the timbre (pronounced tamber; I often hear it mispronounced timber) of acoustic instruments and voices. He looked for any "vowel" colorations in loudspeakers, and with any "grain" added to the source material by electronics. Second was the reproduction of the orchestra’s balance; the heft and weight of the tuba, the double bass, the left-hand registers of the piano, the bass pedals of the pipe organ at one end, the sheen of violin strings, piercing blast of the trumpet, and delicate peep coming out of the piccolo at the other. Plus all the harmonic overtones produced by all acoustic instruments and voices. He valued transparency for the role it played in allowing all the "voices" in the orchestra to be heard. For a stunning example of that kind of inner detail, try to hear any of Bob Fulton’s ARK label recordings. They allow every single voice in the large Minnesota church choirs he recorded to be clearly heard, all the individual threads of the vocal tapestry revealed. He also captured the awesome power of the local cathedral pipe organs. Incredible recordings, fully the equal (if not better) of those of Dave Wilson.
By the way, the difference in timbre produced by two instruments playing the same note is the result of the relative strength of all the harmonics of the fundamental tone produced. The same is also partially true of the difference in timbre between two, say, violins. Partially because there is also the matter of the resonance of the wood used to make the violin, it’s shape and internal construction, and how it is finished. Gretsch drums were for many years the preferred make by players who appreciated their superior resonance, a result of the nature of the design and construction of their shells. All six plies were butt-joined, unlike the scarf-joint construction of all other makes.