Bartok with external headphone amp

I am looking for a little help with an external amplifier. My friend is letting me borrow his XIAudio Formula S to use with my Abyss 1266 TC. When I connect it to the bartok via xlr and the amp is turned up past 60% there is hiss present. The hiss gets worse as you turn up the volume. I opened up the amp to make sure that pin 1 and 3 are connected on the amp. The hiss is there even when the bartok is muted and there is nothing playing.

This does not happen with my other headphone amp (Cavalli Liquid Platinum) or with my speaker setup. This leads me to think that there is something going on with the amp. I am waiting on adapters so I can try the single ended output of the Bartok with the amp as it only has the xlr inputs. Has anyone run into a similar issue??

Have you tried toggling the Gain on the Amp? - seems there’s a gain button at the back). Also noticed that the sensitivity on the Amp is 1V, you might want to be sure your Bartok’s is set for 2V or 0.6V tops. Also, you might want check that both the Bartok and the Amp are connected to the same AC power point to be sure there’s no potential ground loop issue. Stick to the XLR rather than RCA.