Regarding the flat sound vs colored sound and how different components affect the sound in different ways. You know, tubes are warmer, Cowon's BBE adds depth, Ety's are flat and accurate, etc. The observation I have for discussion is this - how can you know? It is a long trip from a musician's instrument to the listener's ears. Say you have a recording of a rock guitarist. Many rock guitarists prefer tube amps for their warm overdriven distortion. Also, maybe the player prefers a touch of reverb. Overall, the original recording is going to have a very warm sound.
So - the point I am making is this - unless you were present at the live performance, you can't know where the colorization (is that a word?) of the audio occurs. This is true for other situations as well. If you have a live jazz recording, like my favorite Wes Montgomery's Smokin at The Half Note, you can't know if the warmth, or depth is being produced by your equipment or if it is on the original recording. The "flattest" gear around had better reproduce that warmth and depth or it isn't flat at all, right? Hmmmm.
We know because they've measured it.
Google Free Field Equalisation and Diffuse Field Equalisation.
Yes, it's going to give you the same sound as a flat speaker - which sounds the same as real life.
Of course there's no mastering standard, so what you're getting is the master sounding as it would if it was played in real life exactly flat.