This site, with tech reports by Arny Krueger, has all kinds of interesting quantitative tests on:
Computer Soundcard Tests
Computer Video I/O Device Reports
Computer Video Card Reports
CD-R Media Tests
Consumer and Pro Audio ADC and DAC Reports
Consumer and Pro Audio Signal Processor Reports
Consumer and Pro Audio Player and Recorder Reports
It also has other useful links and general audio discussions. Some of the test data is rather old - it has tests on the my old SB AWE 32! - but is still worth a look.
http://www.pcavtech.com/index.htm
