Back on track then,
For the OP,
I will share my own ideas of what I deemed as the nearest I could come up with as the perfect preamp for me at the time, which by the way’ I still use in my own system today.
The preamp was designed to compliment the power amps I was building at the time.
These are the attributes I decided were most important, and achievable.
Wide band-width.
Near Perfect stereo matching between channels at all levels of attenuation, and frequencies.
Low noise.
High build quality.
Directly coupled circuitry throughout
Input impedance fixed ie; not affected by attenuator.
Low Output impedance, again that wasn’t affected by attenuation at any position,. circuitry that was capable of driving all types of cables and lengths [realistically]
Without serious drive, and bandwidth limitations.