Using XLR for Phono out

I don't know how the RCA inputs on the GCPH are configured. They COULD be set up for balanced mode, IF the ground connection on the RCA actually carries the negative phase of the audio signal. To test this, you could see whether there is electrical continuity between the ground of the RCA jack (the outer barrel shaped part that touches the flange of the male RCA connector) and the chassis. If there is continuity, then the GCPH is seeing the phono signal as SE. As for your phono cables, do you have a separate wire for grounding to the preamp chassis? If so, then it is possible that you can get a balanced signal out of the cables, if the shield of the cable is not otherwise grounded, either via that discrete wire or at the input jack. It's a confusing mess, I know. Best advice is to enjoy what you've got.

Lewm, thanks for the clarification. Having a conversation once with Jim White of
Aesthetix, I recall going over this point due to the fact that he offers XLR and
RCA interconnects on virtually every possible location of his gear except the
phono input of his phono amp the Rhea. This made me wonder why anyone
would then offer it, for the same reason that we have the conversation time and
time again about the effectiveness of offering XLR inputs/outputs on equipment
that do not truly have a balanced architecture... and I'm sorry to say, no Rogers
teaching English Composition in our family. Architects, industrial designer,
carpenters, a watchmaker, gunsmith... crafty folks but, few scholars.

Spaninc, I would say yes on the XLR from phono to pre!

Happy Listening!

Spaninc, the output of your VPI is in fact RCA balanced, not SE. It would make much more sense to go balanced from the cartridge to the phono preamp, see for example www.mr-labs.net, than from the phono preamp further.

Just to point out a potential fly in the ointment, not all true balanced inputs (outputs too) are created equal. One needs to measure the CMRR (Common Mode Rejection Ratio) at the input. Many manufacturers use OP amps to implement balanced inputs. Most of these have poor CMRR. Also, for good common mode rejection the source impedance of the two halves of the balanced output on the other end should be equal. BTW, though much disparaged by many in the audio community, transformers have some of the highest CMRR ratings and equal source impedance is a given. By my count there are 18 Lundahl amorphous core transformers in the signal path of my system and it sounds great, no noise, hum or RFI interference.

Romaxim, I was planing on connecting RCA to XLR adaptors on the output of the VPI JWM tone arm when I realized the
GCPH has only RCA for inputs. However, outputs from this amp are true XLR so I guess that part is solved by default