[nitrogen]

An increased "clarity" or "spaciousness" of sound can be caused by anything from a slight increase in total gain (even as small as 0.5dB) to bypassing or enabling bass and treble controls, even if the controls are set to zero. Some sound chips also have "3D" effects which mix inverted and/or delayed copies of the left and right channels with each other, that can increase or decrease perceived spaciousness. Differences in power management approaches between the operating systems can increase or decrease electrical noise in the system (more noise means finer details are masked), and could also affect the accuracy of the sample rate clock, resulting in different amounts or types of sample jitter between OSes. There are other DAC parameters (i.e. DC bias -- some chips might be able to produce a balanced signal between -Vs and +Vs, but only if they have a negative supply; otherwise they have to fall back to 0V to Vs) that Linux may be programming differently.

The best way to identify any differences is to run the audio into a calibrated measurement device (at the very top end an Audio Precision box) and check the gain, frequency response, jitter, THD+N, etc.

[neya]

Thank you, this is a very clear and crisp answer. Something I definitely wanted to know about! Cheers!

Edit: Will calibrate and let you know mate. Thanks!