High end stereo preamps? Worth it?

I used passive preamps for many years. Then one day I decided to check out an active. I decided on an Audible Illusions. I was stunned and amazed! The music had structure and substance I never heard.
I now have upgraded to an Atma-Sphere MP-3. Pricey but well worth it.

The music had structure and substance I never heard.

You probably heard tube microphonics/euphonics.
If you put that same source "direct" into a pair of very expensive headphones you will get the sound more similar to the passive pre than the tube. A tube cannot make music it can only amplify and in this case "color it"

Cheers George

@djones51,

unfortunately a digital volume control progressively leads to a loss of resolution as the available bits get truncated. As long as you stay above say 80% of max volume, your statement applies; below, not so much

Analog  volume control is generally better. The truncated bits is true when dealing with 16 bit DACs not so much with 32 bits. 

@georgehifi, could this be harmonics ... ??? ... "color it"