Sound Card with External DAC

Guys, what's wrong here is that "CD-audio data is read correctly in digital by CDROM drives". It's correct for audio extraction with CRC check, multiple re-reads, and error handling, but not for playing CD in CDROM drive. When you play audio CD real-time, the received audio data will almost never be 100% lossless. In this case much better built CDP or Transport easely outperfom any CDROM. But if you do audio an extraction from CDROM to hard drive using EAC and Plextor or another very good drive, that HDD may become a perfect source.

Data IS data, but the way how they read it are different. I would suggest you to read some FAQs about 'how cd-player works'. Shortly, when you read data CD, your drive works on, let's say, 24x speed with buffering, it has enough time to read, check CRC, and re-read if necessary up to several times. And re-tries ARE necessary, due to the nature of CD media. When you play an audio CD, your drive (except Meridians?) has only one attempt for anything, obviously no CRC check performed. The result is not 100% accurate data retrieved, resulting in jitter, which directly affects sound quality.
On the other hand, audio extraction (from CD to HDD with appropriate software: with CRC, re-reads, variable speeds, etc.) is much closer to the way how data CDs are processed, and thus a perfect copy may be obtained.