Good thread guys even if it did go off topic a few times.
Earlier in this thread it seemed there were some different ideas thrown around about how these PC systems can be used. Talk was made about using "enhancements" in the PC to improve sound quality.
I think we needed to seperate using a PC as a source and then using a PC to do "enhancements" like time alignment, cross overs, EQ, etc...
Some people don't have a high end sytem and want to use the PC for all of that. I don't think the hardware or software exists for that yet. In this instance a PC would not be equal to a head unit.
The Alpine processor that Red, and others, are using is basically a computer in itself. The PC and sound card are simply creating a digital sound output (optical or coaxial, doesn't matter) which can be of very high quality as there are no analog parts being used (basically). Even some mobo's have digital sound outputs built in.
The computer in the Alpine takes the digital signal and does all the processing, including EQ, time alignment, etc... and then uses it DAC's to output an analog signal that the amps will recognize. That's certainly a good way to do it, but requires all new equipment, usually. Now this setup can be better than a head unit as Red has shown in competition.
The non audiophiles get by on basic analog sound cards as the sound is pretty decent and they are not too picky. In this instance, a PC and basic sound card would not measure up to a head unit.
I seem to fall in a different category as I already have a complete high end sound system which has a digital pre-amp, digital 28 band EQ, and digital x-overs using the Rockford EPX2. What I want to do is use the computer to replace the traditional head unit as the music source. So I need just a pure, clean output with no added processing or sound enhancements at all. Pretty much a straight in and out source. I think a PC with a professional audio card will get the job done and this setup will equal or better a head unit.
So far what I have found is a cheap sound card, the Chaintech AV-710 for around $25-$30. It uses a mediocre 6 channel processor, but since it is a 7.1 card the 2 additional channels use a high quality Wolfson 2 channel DAC that can handle a high sample rate, capable of a much more robust 192KHz, and full 24 bit resolution. These 2 channels can be configured to act as the main outs and provide a very high quality stereo output for little money. If other people are looking for a cheap but fairly high quality sound card for their car PC, then this is worth taking a look at.
In a higher price range is the ESI Juli@ (julia). It runs about $140. You can read about it here:
From everything I've read, it surpases the M-Audio Revolution cards for sound quality and specs. This is the card I may go with to get the high quality sound that my CD player currently provides.
For those that don't understand bit rates and sampling rates here's a nice little explanation that makes a lot of sense: