My dad has connected his Jensen speakers to a Pyle PT270AIU pre amplifier system, but when the machine is turned on, a high pitched siren noise is produced from the speakers which doesn't change no matter how low or high the volume is set. The noise occurs even when I switch through inputs. Is a problem with the amplifier system or the speakers? The PT270AIU was recently purchased, but we've had our Jensen speakers for many years. By the way, I am not really audio tech savvy. I've been reading through threads that seem to have similar problem, but I have no idea how to start troubleshooting. Maybe I just need to exchange it for another system? Thanks!