The negative effects of an extra connection at this low of a signal level are real.
Frankly, I wish Tri would have eliminated the RCA junction box instead of offering yet another way to compromise his fine tonearm.
The Discovery Cable issued with the arm is very, very fine cable. For the record (pun intended), Discovery used to supply Air Tangent with wire for their tonearms.
My point is, that I don't know how it's possible to get a wire that is so superior to the standard issue Discovery Cable that it overcomes the disadvantage of the extra connection you've added to the mix.
As I advise customers on a regular basis, that their best bet is to stick with the standard issue, or gamble on a complete rewire - still retaining continuity from cartridge clips to output connectors.
Since you're likely to make a change rather than an improvement, why not just experiment with cartridges for a flavor change?
Thom @ Galibier