LYD: 6 dB difference between left and right

Using XLR inputs, I have a difference of 6 dB level between Left and Right monitors with same settings

If you find a difference of 6 dB between the 2 speakers and you need to set one of them to the next  level setting e.g. one at -6 dB and one at 0 dB to balance them, please check: 

- You are using balanced cables on both side and they are in good state. 

- If the other end of the XLR cable is a TRS 6.35mm jack, make sure it is fully inserted into the output female jack. When the TRS jack is inserted half way, you still get signal but it will be an  unbalanced signal coming through. 

If a balanced cable is faulty or not acting as balanced cable, then you would often loose 6 dB level.