Here's an interesting perspective, related to digital vs. analog, from my EE friend. As I've said on other threads, we discuss these topics and many more at work.
"Everything you hear ultimately is traduced through the fully analog mediums of speaker cones and air movement. Because of this, the ultimate audible result of a digital signal is a fairly smooth analog wave. Even if you have only 3 points to determine your wave versus 20 on an SACD or "infinite" on a record, how different will those representations be if you are at the upper frequency limits of the transducing surface? The surface of the speaker cannot instantly transition from full excursion in a positive direction to full excursion in a negative direction, so at some point, because time and motion are involved, the speaker produces the exact same waveform from a three point digital reference as a full analog signal. This would effectively be a "distortion" of sorts with the ironic result of being closer to the original signal.
A vinyl record effectively contains "infinite" data points, which is obviously more information than can possibly be contained by any digital medium. However, at some sample rate (it would depend on your D/A converter and amplifier), the analog output from the amplifier will be identical regardless of whether or not you use the record or the digital recording (assuming that your components are so well designed that they don't individually "color" the analog outputs as you suggest they may).
The ultimate result we are comparing is the audible output from the speakers, and while the D/A converter, amplifier, and speakers may all carry through some of the reduced resolution of a CD recording, there is a point in the digital realm (possibly SACD) where the end result reproduced by the equipment will not differ one iota."
To put my spin on it, at what level does the digital signal become close enough to the analog that the physical restriction of the speakers themselves are the limitation.
I have a difficult time believing that the groove in a record can really contain the same level of detail as a CD or certainly an SACD and that a mechanical needle can track this level of fidelity. So is it really a case of the digial signal actually containing more information than the analog and the analog is "smoothing" things in the digital signal that the speaker is having difficulty reproducing?