Why do digital cables sound different?

Redkiwi, the overshoot and undershoot you speak of is caused by capacitance in the cable. While overshoot and undershoot themselves may not necessarily effect the DAC output signal, the capacitance in the cable may effect the data pulses risetime. This effect, I would assume may be audible. While jitter is a degrading factor in a system of this type the transmission cable is not likely to increase or add jitter to the bitstream. I feel capacitance is the real culprit here. The less capacitance in the cable the better.

Ehider, I am still the skeptic, but I appreciate your viewpoint and candor. BTW, Is your employer Burr Brown? Thanks for the reply.

I will be honest and say that I do not use fiber optic cables so I can not say definitively there is a sonic difference between digital cables. You have heard differences, so I will take your word for it. As for the reason.... I am an EE not a physisist. If I were to take a stab at it, with my limited knowledge of optics and lightwave, I would guess the differences would be due to propagation delay, loss or refraction differences in the cables. Maybe someone else with a better understanding of optics in this forum could enlighten us both.

Don't worry about starting a religious war. The reason for these forums is to get the big picture. There are a million opinions out there and you should consider the ones that make sense to you. Part of the fun of these forums is to learn a little and give a little in return. I read a reply to one of my posts the other day that mentioned that audio was a "passionate undertaking". I subscribe to this wholeheartedly because if the music we listen to and the equipment that provides that music does not empower emotion and passion, why listen at all? If some of the responses seed a bit emotional, just understand that it is only because of the passion that we have for the music.