Is the preamp the “heart” of the system?

Now replacing my Audible Illusions M3B with John Curl phono boards with an Atma-Sphere MP-3 to match my A-S M-60 amps.
I agree the preamp is the brain and that the amp is the muscle and the speakers the legs or the voice. Then the amp would be the air from the lungs.
Believe that a great preamp can transform a system!

Yes, yes... a straight wire WITH GAIN!
Passives mostly have the straight wire part but not the latter.
But “uncolored” is highly subjective. I think that preamp manufacturers all have their own idea of what music sounds like and embues their pre with their “house sound”. Or “no sound” if you will.
But no sound is not necessarily desired. I think the safest and, hopefully, the best choice is to match the preamp with the amp by using units of the same manufacturer. I have found an amp in which I love the house sound, Atma-Sphere. I believe it is unique and special. So, I want to emphasize that sound by using an Atma-Sphere preamp. I think and hope that this match will be my destination units. And the amps work great with my speakers. Off the merry-go-round!

Hi George,
You are right... kind of.
When I talk about gain, I actually refer to "meat on the bones".
I lived with passives for decades and when I finally tried an active, I will never go back. I am not a tech guy but I think that this aspect has a lot to do with an active producing musical information that could be referred to as gain.