OK kind of a strange senario. I have a set of Boston Pro60 running off a Zapco 360.4. Once in a while the amp would go into protect. When the right rca was not plugged in it would not go into protect. Just touch the RCA to the input and it would go back into proctect for a few second at a time then turn back on for a second. I was told to send the amp in for repair, came back clean. No problems. Reinstalled it, worked great for about 2 months, started up again. I check the ohms from the speakers and coming out ot the crossover. Left side- tweeter @6.0, email@example.com at the crossover the same, and at the output to amp @3.5 roughly. Right side- Tweeter @6.0, speaker @3.4-3.6, at the crossover same. Heres the kicker. When the amp was going into protect I checked the crossovers showed the same at the inputs from the spakers and tweeters, but the right crossover output was fluctuating from under 1ohm to 3.6ohms. When it was working normally the ohms showed around 3.5ohms. So I guess the crossovers going bad???