How to accomodate a balanced only phono stage ?

Dgarretson has got it pretty close. The gain of the preamp is unaffected by using only one input single-ended; the problem with that is noise that is now available at the input of the preamp, whereas if you use the signal balanced, the noise can be rejected, and just as important, the input cable will have less artifact.

I am really impressed at the increase in knowledge in the community regarding this subject!! Only a year ago there would have been a lot more myth-information present on a thread like this, so far the only such posts have been two from one 'goner. Well done!

English is not my native language and I don't really know that much about cartridges. But if I were to buy a phono amp like the Blue amp Surzur, which to my knowledge is of a fully balanced design would I benefit from using XLR cables.
The junction box on my VPI scout can be replaced by a XLR junction box. Or should I just use RCA cables.

In addition does anyone have any experience with a blue amp Surzur?

Mordante, your best option in this case is to replace the junction box with one for XLR cables, and run everything balanced. The advantage of doing this is that the cables will have less overall effect on the sound- they will be more neutral.

You can run cart. balanced into phono pre with RCAs if cables and input jacks are wired that way. That is the way I run mine. XLR jacks are too big to fit through my arm mounting hole (OL arms use Rega mount with hard wired cables). In my case using XLRs would require unsoldering them every time I needed to pull the arm. :~( No real penalty to using RCAs wired balanced IMO. The shield can be grounded at the turntable which is then grounded with the TT ground wire.