Hi, I have two Rane AC23 active crossover. They are not the same generation, one with external power supply and the second with internal power supply.One is older than the other. When I try to hook them up in 4 way mono, one (the newer, external power supply) play much louder than the older one. Could it be possible that the older one have some bad caps or resistor. If I have to chance all capacitors, would it be valuable to upgrade to poly cap. Could it be another problem???. I'm now using them in serie. One is for low and low mid , high out goes in the input of the second for high mid and high.Somebody told me that I will have phase shift problem that way. Thanks for your advice.