I read something similar a while ago about length of digital coax cable. I can't remember which company it was, but they were talking about the ringing in the cable. Some of the signal echos in the cable, and if the cable was less than 1.5M long, then the digital echo could interfere with the signal currently being processed. They claimed that 1.5M was the shortest cable that should be used for digital connections, but I found it funny that after explaining all of that, that company sold 0.5M, 1.0M digital cables as well.
