Music is coloration- ie. a blend of sounds and overtones and the nuances of tonal responses. Every instrument, violin, piano, ect. has its own unique coloration as it were. If your system can resolve the differences of one violin to another, for example, then I would think that is a very good stereo.
Trying to reproduce exactly what the recording engineer heard is an exercise in futility. Even if the recording engineer came to your house, he will not remember every nuance of tone and detail from the original recording session.
In the end your system will have the imprint of your sonic signature on it just as someone else's system will have their sonic signature. When I lived close to some hifi buddies in South Bend, In and Niles, Mi, we would come around and listen to our respective stereos and we all eventually agreed that we had some nice systems, each one being unique with their own +'s and -'s. We concluded that all systems will have their own unique sound and could enjoy any one of them. Additionally, the set-ups varied depending on our listening tastes as well. One friend was big into classical and did not like brightness one bit.
My system has changed over the years- I hope for the better, as my tastes have changed and as influenced by hearing other systems.
I was at a recital at my son's University a few weekends ago. An intmate, acoustic setting with a Grand Piano, flute and vocalist. (The vocalist did not use a microphone.) I was fortunate to sit 2nd row center seat. During the performance I closed my eyes and I could have been sitting in front of my stereo. The music was very satisfying and I was pleased to hear strong similarity to my stereo system in terms of tone, imaging and resolution. Would someone else that sat in that room and then in my living room come to the same conclusion? Perhaps but maybe not.
Flat frequency response in your listening room achieves nothing- that was my point.