This unit is new to me. The crossover is inserted between a bryston preamp and amp. There is about a 3 dB between left and right channels. I`ve double checked cables and no difference. I can use the high pass level or the balance knob to balance things but it bothers me that there is that much difference between channels. Is it a quirk or should it be sent in for a check up? There is 2 or 3 years warranty remaining.