Earlier this evening, while setting up for a little 'shedding, I plugged into my PHA-1. As I turned the volume up to about 25%, I noticed there was no sound coming from my headphones. I then increased the volume to varying levels up to 100%. The volume did not kick in until 100%. I tried using both High and Low inputs, but I got the same results. Is there a simple fix for this probelm (i.e. trip to Radio Shack), or, should I send the PHA-1 in to get repaired?