Criticality of digital cable impedance in jitter reduction?

[Boomzilla]

I think this question is for KeithL and maybe for DYohn? I'm using a rig with an AES/EBU connection between the streamer and the DAC. The femtosecond clock is in the DAC. Since I didn't have any digital XLR cables in house, I'm using a plain audio XLR cable for this connection, but I've read that using a low impedance cable, such as I'm currently using, is more prone to cause unwanted jitter.

Since 110 ohm digital AES/EBU cables are cheap, I'm ordering a one-meter one anyway, but my question is: How critical is a 110 ohm cable to digital transmission, and just how much jitter could be generated by using the "wrong" cable?

Thanks - Boomzilla

And a follow-up question on a different topic - For vintage transistor amps, replacing the power supply capacitors is common, but for those older amplifiers, the thermally-conductive paste on the output transistors is also typically dried out. Would it be worthwhile to replace the thermal grease on the outputs?

[DYohn]

Realize that the impedance rating on the cable has nothing to do with resistance or actual impedance of the cable. 75-ohm cable is based on a BNC or RCA connection that creates a 1-volt P-P signal into a 75 ohms termination. 110-ohm connectors are the professional AES standard to create a minimum 2-volt P-P signal into 110 ohms. So the rating is for the connection type. If you use a "standard" XLR cable between 110-ohm connections you will generally be fine. Specially-rated 110-ohm cables are only so-rated because they have been tested to comply with the AES standard. There is nothing different about the actual cable other than this certification. The only time you can run into issues is if you are connecting a 75-ohm and a 110-ohm together, such as using an adapter to connect an AES output to a BNC input. Both signals are the same (comply to S/PDIF) but the voltage levels are different.

[DYohn]

As to your second question about rebuilding amplifiers, you are much more likely to damage an old transistor by unmounting it to get to the grease than you are that the grease needs to be replaced. IMO, anyway. I'd leave it alone.

[Boomzilla]

Thanks and thanks again, David. I appreciate it.