elikd - First off let me say I don't necessarily disagree with what you are saying. I do think there is an art to Analog PreAmp design that very well may be audible. Maybe not to you or me but I would not be so quick to dismiss it. As you said a tube Pre actually colors the sound. I believe the "Art" of analog PreAmp design, even solid state ones can have different electrical and sonic characteristics. Who knows if it is audible? Do you really believe all reasonably designed PreAmps have the same:
1- Flat Frequency Response
2- Noise and Distortion levels below audible thresholds
3- High Input impedance and low output impedance?

If not, I don't believe it is fair to say they are all going to sound the same. Just to be clear I'm talking about just the analog PreAmp section not the digital PROcessing. I disagree that the function of a PreAmp "is to simply transmit sound and not modify", it does condition the signal that is the function of a PreAmp. As I am a big user of the bypass modes I'd be very interested in comparing those modes between the 950 and 990 and can very well believe there may be an audible difference between the two.