Hello, noob here. I just finished building the Crack headphone amp and built and installed the Speedball upgrade. Prior to the speedball upgrade my voltage reading from the phone jack spiked at about 12v and quickly dropped down to 0v. I know the manual says it shouldn't go much past 9v but now with the speedball upgrade the voltage now spikes up to 27v but, again, quickly drops down to 0v. All other voltage readings are within acceptable levels. Should the higher reading I'm now getting be a concern since it does return to 0v almost immediately ? I have not yet plugged in a pair of cans and would like some feedback/causes before I do. If it's a problem where should I start on finding the cause of the higher reading?