Unbalanced to balanced VPI junction box change?

Why rewireing or upgrading tonearm wiring?
You can use common ground + signal pins on each balanced recepticle.
There's a 5-pin balanced recepticle as well with R+-,L+-,G just like in this phonostage:
http://www.violectric.de/Pages/en/products/ppav600.php

If you plan to run the cartridge (which is an inherently balanced source) in balanced mode, one thing you might consider is the fact that you will have a low impedance balanced line connection, which in plain English means that you will not be able to hear any differences at all if you change the wire.

This is because a true balanced line connection has that much immunity to interconnect cable artifact. So no worries!

I have an XLR junction box...no need to change from Valhalla (unless you want better sound - I had Nordost and now have Discovery...in MY system, it sounds much better). Just get the junction box and install it yourself ..easy to do.

Pbnaudio is right in that you should be able to swap out the junction boxes. You should be able to use the Nordost you already have in the tonearm. Looking at your system, you show a Sim phono stage. Its fully balanced, of course, so it does make sense to switch to balanced on the TT. If it was my system, I would do it. It shouldn't cost anywhere near $1000 unless you need a new cable to go from the TT to the Sim.

"This is because a true balanced line connection has that much immunity to interconnect cable artifact. So no worries!"

Are you talking about just tone arm cables, or all balanced cables? On fully balanced components and IC's, I can definitely here differences.