Troubleshooting balance issues

I'm hoping to get help troubleshooting balance issues I'm having with my system.  

Pre Amp is Parasound Halo P5.  Amplifier is Emotiva XPA-200.

I'm getting between 1.5-6dB less on the right channel than the left.

Below are the troubleshooting steps I've taken. I'm hoping you might have a couple other ideas:

• All testing either with Mono recordings or single channel pink noise
• Tried different interconnects
• Ensured all connections good
• Tried balanced and unbalanced connections into the emotiva amp
• Tried through two different preamps
• Swapped L/R output from amp to speaker and balance issue stayed on R output and switched to other speaker
• Moved/swapped L speaker to the R side and vice versa
• Measured L and R put with single channel pink noise
  
• Swapped L/R 

Occasionally on a power cycle on the amp it will come back centered. Occasionally I'll get a full day centered. More often than not the R channel will be off -1.5 to -6 dB. The about of gain loss seems to stay stable (i.e. If -1.5 it will stay -1.5 for a while).

Would appreciate any additional ideas!!  

Thanks :)