XLR to RCA conversion


I am using a balanced preamp (Atma-Sphere) with a single ended power amp (Primaluna).
It has a ground loop hum that I can’t seem to get rid of.  I am told a transformer will probably work.  Can anybody recommend an XLR to RCA transformer that will work?  Brand, model, and who sells it?

Thanks in advance!!

hifinut51
Post removed 

Whirlwind ISOXL Line-Level Isolation Transformer, 3-Pin XLR Male/Female Connectors at Amazon

Jesse at Pine tree makes a balanced to unbalanced converter. It is an amazing piece. I use it between my Lumin D2 and amplifier. 

Ground loop.
Power amp should have grounded AC.
Lift ground to the preamp.

Use only unbalanced RCA interconnects.
Unshielded twisted pair is best, by far.
Unless the system is balanced in and out, there is no advantage to a balance XLR cable. No need for a transformer or other performance robbing accessory.

K.I.S.S..