Channel unbalance in active crossover

[KanedaK]

I have a slight channel unbalance in my active crossover.
I don't think I can hear it, because it seems to be on the low pass only, but I can see it because my bass amp has LED vu-meters. The LED for the right channel is always slightly above the left channel. If I go straight to the amp without going trough the crossover, the problem disappears.

I'd like to know what possible causes it could be.
Crossover has new electrolytics, new coupling caps, new opamps in sockets.

 

[JonSnell Electronic]

Component tolerance? Coupling capacitor? Low gain on low output one side? Bass amp not calibrated correctly?
Use a known frequency to inject and trace through the signal path.