Using XLR for Phono out

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

Buddy,
using adaptors (XLR RCA, or what ever) with *any* phono-cable is one big NO NO!
So my advice: DON'T!
BTW, the GCPH wants to see a single ended (RCA) input, and only then it is converted (via OP-amp) into a differential signal and further handled like such. So the GCPH is not fully differential from input to output (kind of demi-differential :-)
It is this OP-amp chip XLR conversion at the input that makes some purist cringe, and some not bother to use the XLR output (unless desperately in need of the extra 6dB I mentioned earlier on)
Greetings,
Axel

VPI arms can have either a junction box that accepts XLR cables, or one that accepts RCA's. If your equipment is REALLY balanced from input to output as Ayre stuff is, with no electronic trickery in the circuit to make the single ended circuit balanced, there will be a definite advantage in using balanced from cartridge to speakers. The difference is not subtle, if and only if you have the proper gear to accomplish this.

The type of plug does not determine whether a connection is balanced or not. I am using a "balanced" connection from my cart. to my fully differential phono pre. However, by choice, I am using RCA plugs. Why? XLR plugs fitted on my OL arm would not fit through the arm pod on my Nott. table. Balanced or single-ended is a function of the circuit topology, not the type of plug used.