I've tried five different digital cables with my current setup and have heard varying degrees of differences. In some instances there were slight volume and tonal differences, and also differences in soundstage size.
75 ohm hasn't always been the best in my system either. One that performed very well was 110 ohm, and the other that was very good was no different from an analogue RCA, so you never know. Both of these threw a much bigger and more lifelike sound stage than some highly regarded 75 ohm cables.
As with anything in this hobby, it's all about synergy and sometimes specifications can't predict that.
75 ohm hasn't always been the best in my system either. One that performed very well was 110 ohm, and the other that was very good was no different from an analogue RCA, so you never know. Both of these threw a much bigger and more lifelike sound stage than some highly regarded 75 ohm cables.
As with anything in this hobby, it's all about synergy and sometimes specifications can't predict that.