Does itunes colour the sound?

It is BOUNCING that colours the sound. Do some searching on the DUC and you'll find countless threads of debate on this topic. Something happens in the summing phase that seems to affect the quality of the sound (I happen to agree). As a result, many engineers have taken to external mix summing. On the other hand, a lot of people claim that mixing "in the box" sounds fine and doesn't affect the mix.

iTunes definitely colors the sound. The older versions were kind of a green, and sometime recently it appears to have switched to more of a blue.... Have you made sure the sound enhancer is off under playback preferences? Re: bouncing to disk changing the sound vs. playback, all I'll say is, do the null test.

What file format are you listening to? Are you compressing the music with mp3 or AAC? iTunes uses Quicktime to play the files. If you are listening to AAIF playback, there will be no difference.

Maybe you mean what is more important, "objectivity" or "subjectivity". From Wikipedia, the free encyclopedia: Objectivity (philosophy), encompassing distinguishing references in the field of epistemology regarding the ontological status of a possible objective reality, and the state of being objective in regard to references towards whatever is considered as objective reality. Subjectivity - refers to the property of perceptions, arguments, and the language terms use to communicate such, as being based in a subject point of view, and hence influenced in accordance with a particular bias. Its opposite property is objectivity. When comparing audio samples, it is best to be objective.

And how many music consumers listen objectively? Or audiophiles for that matter? It is all about sound. If a mix sounds bigger mixed outside the box than inside, yes that is a subjective thing. You can't hear the sound of double-precision math but you can objectively measure it.