I have always wanted to have a system centered around a windows computer rather than a car audio head unit. I am curious as to whether I would notice an audible difference between the sound quality of music coming from a computer as opposed to a nice head unit. I cannot find output voltage in the specifications for computer audio cards. Will I be able to hear the difference? Also can you hear the difference between deck with 4V preouts and a deck with 8V preouts?
The answer to your question is yes there is an audible difference between a computer and a audio cd player, generally speaking computer outputs are low voltage and high impedance, they are designed to be a computer first and not an audio source. Between brands there is a drastic difference in sound quality and preout voltages. Very very few of the cd payers that claim a 4 volt or 5 volt preout actually make that much clean voltage, they generally have a high output impedance and clipping preouts. One of the few cd players that have actually made what they claimed is Eclipse, they generally have a true 8volt rms non clipping (0db) preout at a low 55ohm impedance, this is part of the reason why an Eclipse is a little more than evey one else. The lower the impedance, generally speaking the better the sq, the tradeoff is immunity to noise, it costs Eclipse more $ to keep the noise out and maintain SQ. A non clipping preout gives you just that, a cd player that can play to full output and not distort the audio signal, again this costs more $ and most companies will not pursue an audio signal to this length. It is well worth your time to listen to a cd player like a Kenwood and then install a 5volt Eclipse in the same vehicle on the same system, your ears will tell you the rest.
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Top Secret, I can tell you but then my wife will kill me.
I'll second what Rob has posted, but also add that the output quality from a computer depends entirely on the sound card in the computer. Systems with built-in audio or cheap $12 sound cards will sound like hell. But good quality sound cards will exceed CD recording quality easily. I have a PC-based Digidesign Pro Tools digital audio workstation with sound quality that will blow away any head unit I have ever heard. The good quality Sound Blaster card in my laptop connected to the line level AUX inputs on my Nakamichi HU can sound far better than a factory recorded CD. So, it depends!