RCA to XLR adaptor causing amp to shut down


Can anyone help guide me please: Using RCA to XLR adaptor causes amp to shut down going into protection mode. The application is Luxman 595ASE pre out RCA to XLR on Avantgarde Duo Mezzo XD active base units.
When using Mark Levinson pre RCA out this works fine.

Opening up the adaptor, pins 1, 3 and what I assume is an earth tag are linked with pin 2 connected at the RCA end. I tried cutting the connection between pins 1 & 3 and this stopped the shut down but introduced a significant hum.

chrispb1

Cardas makes an XLR to rca adapter that floats pin 3.  All the other adapters I have used tie 1 & 3 together which can short out some electronics. 

If your amp is not using the XLR pins in the proper configuration, I can see how this might happen.- That the Levinson works would seem to confirm this.

B