CD Ripping software

Modern computer processors and motherboards dynamically vary both cpu voltage and cpu clock rate as processing requirements vary from instant to instant. It would seem conceivable, depending on the particular hardware, that noise transients associated with those abrupt changes in voltage and clock rate could contribute to jitter on the computer's digital output that is being used, with those noise transients essentially bypassing intervening circuitry. That kind of effect could conceivably be sensitive to the cpu's involvement in decompressing losslessly compressed audio files.

The fact that the decompression process does not represent a heavy load for the cpu may actually worsen the severity of this effect, because it could result in frequent SWITCHING of cpu voltage and clock rate that would not occur under an essentially continuous heavy load.

It would be interesting if those reporting sonic differences between playback of different lossless formats were to see if those differences persisted when all of the computer's power saving features are disabled. That would include "Intel SpeedStep," which can be disabled in the BIOS of many computers, and, for Windows 7 machines, the settings change I described here (which did in fact resolve the playback problem reported by the OP in that thread).

Regards,
-- Al

10-10-11: Mapman
I really like using network players, especially wireless ones, as the digital source feeding the DAC because a network player like a Squeezebox connected to wireless LAN has no electrical connection to the rest of the computer gear that it sources from. I like that level of isolation from the computer domain as an insurance policy against potential noise introduced by gear that is not designed necessarily for hifi audio.

Excellent point, Mapman.

I would imagine that in most cases wired as well as wireless network connections would provide effective isolation from the effects of computer-generated noise, despite the presence of an electrical interconnection in the case of wired ethernet. In both cases the packetizing and buffering of the data that is being communicated over the link mean that jitter at the computer interface becomes irrelevant.

All of which of course suggests another experiment those reporting sonic differences between lossless formats could do, especially if their computer does not have provisions for disabling the power saving features that cause cpu clock rates and voltages to fluctuate, as I described. :-)

Best regards,
-- Al