I have a new Mic Mechanic 2, and an AC power supply, 9V, center negative, plenty of current... When plugging it in, i only get a red blinking light. If i put batteries in, it works, and it continues to work with the AC adapter then plugged in. Are batteries required to be inserted even when using an AC adapter to complete the circuit? If not, what else could be the problem? I check the power supply with a multimeter and it's supplying 9v and the polarity is correct.