This blog post sums up the influence of jitter in the recording-storage-playback chain in three simple but sound statements. [Some additional insights and reasoning are given in brackets.]
Note: Statement two rules out systematic differences in the playback of bit identical files due to differences in noise stored along with the information (e.g. through varying strengths of the physical representations of 1s and 0s) when playing from RAM.
1) Jitter during analog to
A commonly stated "scientific" reason for alledged audible differences between (speaker) cables is the fact that electrical signals travel at different speeds for different frequencies.
The characteristics of a cable are often simplified to its impedance (Z), its capicatance (C), and its inductance (L) where Z = sqrt(L/C). This is a simplification of the more complete formula Z = sqrt((R+j*2*pi*f*L)/(G+j*2*pi*f*C)) where R