so How and Why would a active premamp, tube or solid state sound better than a more direct connection.
Would capacitors, opamps in the signal stage of an active be better than a single resistor, or similar ldr, autoformers?
Every opamp, resitors, capacitors sounds different, possibly changing the sound to ones preference. Adding on your favourite powercord, interconnects, vibration control on these active component adds to the variables you hear, hence the difference in sound.
There is no right which sounds nicest, but the less the variables and carefully matching wiring and connectors will give the best, less molested sonics.
If one has a robust sounding front end, a passive will give equal or less coloured sound. Impendence matching and possible size of speakers room etc will cause possibly a lack of gain required for the amp and speakers to perform or rather not sound thin or dead.
Conclusion would be a matching choice of factors.
The best part is passives are way cheaper and can provide just as good a sound as a $10k or higher preamp.
There is just so much more ways to tune the sound say with capacitors in the signal. Some sound clean or bright or warm or more open pr more distant, the list goes on...
Add the same capacitor in a passive and the traits will start to show.