My friends and I did a rather exausting comparison last year. OK, on a very revealing ($20000) system, disks copied from a hi-end Meridian transport to a ridiculously expensive professional Marantz CD-R were slightly better than the originals. This is probably due to the "pre-groove" on the blank CD-R disks that eases the load on laser tracking mechanisms. On lesser CD-R recorders the copies were very close. We could easily hear the loss of quality from the dual deck Philips, but not so from the expensive consumer Marantz or the professional Otari. Using a computer CD-R we also heard the loss of quality, especially when reading above 4x recording above 2x. This was manifested as harshness (Plextor) or mudiness (Yamaha). On the Meridian-Marantz setup we also heard differences between different CD-R pigments; the feeling was that Mitsui, Fuji and Verbatim were the best. This may depend on how well a particular laser works with a particular dye. However in my $3000 system the difference between the original and a computer-copied CD at 2x is audible only on reference quality recordings.