What is the most important cable in your system

Perhaps the primary power cable (Shunyata Alpha v2) that connects to my passive mains power block (Shunyata Denali v2) feeding the whole frontend of my kit from the city mains source. The interconnect cables from my preamp to mono block amplifiers might well be the most significant if it were not for the dual differential balanced topology of the Atma-Sphere gear on either end. Which renders the cable basically irrelevant beyond a decent Mogani studio grade XLR. 

The power cable. Without it, nothing works.

@sandthemall 

I agree too, phono cart to phono amp.  Because the signal is so low level it needs all the help it can get transmitting the music truthfully and without external interference or noise.

With a parallel tracking arm I need to use silver litz wire into locking plugs and junction box.  I run my whole system balanced so I can use high quality XLR terminations and from the box to the phono amp. 

@clearthinker 

Yes, that was my thinking also: what is tiniest, most delicate signal? Even with a higher output MM cart, it is many times smaller than a typical preamp to amp signal.

a lot of back and forth, here I am not a engineer but I do know that overall quality in any process is only as good as the weakest element. Goldratt in his Theory of Constraints called them bottlenecks or friction points. So with that as a guide and from a cost efficiency persective, shouldn’t all cables be of equal quality in a system. Obviously, in reality we may have varying quality of cables and to use what we have is a necessity for most, in that case end the chain with your best so as to capture as much as possible of what the front end pieces is sending. Pre to power