Does OS X process sound in any way other than volume adjustment before outputting it? Some Windows systems have various "sound enhancer" functions enabled by default (depending on the audio driver).  This changes all sounds that are sent to the speakers by applying equalisation and possibly mixing together the right and left channels of stereo sound for a "better surround effect".

I would like to know if OS X applies any similar transformations by default, and if yes, how I can turn them off.

I need precise control over sound output for a physics experiment with two speakers.  I would like to play a pre-generated wave file exactly as it is, without any post-processing.  Most importantly, the two channels must not be mixed at all, and preferably no non-linear transformation should be applied to single channels either (this is less important because some non-linearity is unavoidable when the signal goes through the analog hardware).

Note: The question is about OS X in general, not about iTunes, which does include a sound enhnacer.  I won't use iTunes for playback.
I believe the output is unmodified except for amplification.  For specific settings, you might find the Audio MIDI Setup utility useful as it includes per-speaker amplification settings.  As I'm not a big audiophile I can't attest to the specific settings you mention but that's where I would start to test things out.