Is tonearm cable the most important cable in the system ?

The cable is much less critical if you can run it balanced into a balanced, differential phono preamplifier.

@hifiman5 Good point.  Your cables should be treated as a component itself.

Yes of course every cable is important but not necessarilly equally important in each particular system. Often the closer to the source the more important. I am not talking about power cords now.
When upgrading, most of us cannot afford upgrading all the cabling at the same time, especially when doing serious upgrades.

Leeds - I wonder.... where exactly would you get a seperate ground reference for left and right channels in order to run a "truly balanced" XLR cable from a phono cartridge that has only 4 pins (left/right +/- )????  Stereo Phono cartridges are INHERENTLY balanced devices no matter what connector you happen to be using at the phono stage.  

jwpstayman

... I wonder ... where exactly would you get a seperate ground reference for left and right channels in order to run a "truly balanced" XLR cable from a phono cartridge that has only 4 pins (left/right +/- )???? Stereo Phono cartridges are INHERENTLY balanced devices no matter what connector you happen to be using at the phono stage.

You’ve answered your own question - a phono cartridge is inherently balanced. If you connect it to a properly balanced differential phono preamplifer, the cable will be much less critical - that’s the nature of a balanced circuit. As for XLR cables - I never mentioned them. As you note, you can have a balanced connection regardless of the connector. In this instance, you get the separate ground wire from the pickup arm - almost all pickup arm cables include the separate ground.