TOPIC:

Hi,

I'm using the calibrated files for my EARS, however I'm seeing huge 4.6khz spikes on every headphone I measure  
  
Is this expected, or is there a setting in REW I can change to fix this?

thanks!  
  
 

Yes this due to phase cancellation. You have audio going through the ear canal hitting the eardrum. After hitting the ear drum the wave form is partially reflected back causing the cancellation.
This creates an extremely high Q in a negative direction causing significant reduction in SPL  dB. Your probably using the Calibration file L-HEQ xxxxxx.txt or R-HEQ xxxxxx.txt. 
Try using the Calibration file L-HPN xxxxxxx.txt & R-HPN xxxxxxx.txt. This will change the negative High Q to a lesser value into a slope. Even though it exists you won't be able to hear
the difference. You can adjust this manually in REW by going into the EQ filter Settings 10 EQ's will be available by modifying the exact Frequency, the  Q value between a Q of 1 or a Q of 2 and the Level within the 1st filter on the top. Then select the Match response to target and REW will do the rest. Have fun!