digital cable differences

Hi all, as we all know there are differences in digital cables. I hear also a difference between cables in loudness of sound. When I insert an old Goldmund Lineal between my CD-transport and DAC not only the sound is less loud (with exact the same preamp volume level) in comparison with another cable (I'm using a very simple MITerminator IV line level interconnect as a digital link) but it also sounds less involving. Does this mean the Goldmund is not a good match for the CD-transport (CEC TL-0) and DAC (Bel Canto 1.1) or is the cable defective (conductor breach). I red once that when a digital cable is functioning properly we can hear an increase in "loudness" of sound in comparison with a cable that is not designed for digital transmission or a poorly designed one.

Regards,
Dazzdax