Last week I bought a used TH500 from a friend that changed his rig to the AG-700. He's a stand-up guy so I don't believe this issue was something he experienced. I'm curious if any of you have had a similar experience. My hope is that I simply have a bad speakON cable or power cable. Last night, I was finally able to play through it at my place (the Aggie SL112 with which it's paired just arrived). My other cabs don't have speakOn inputs so I was unable to home test it prior to last night. First of all, the Mute engaged by default after powering up the unit (for the record, my buddy told me this happens when he and I demoed the unit at his place when I made the purchase). This isn't really an issue but figured I'd ask since we're here talking about this. Is this normal? The real concern happened after I played through the rig (for the few minutes I had) to test it out last night. There was a static sound coming from the speaker right before the head received signal from instrument (Fender Elite Jazz). The static was present in both Active and Passive modes from the instrument. Finding it odd, I unplugged pretty quickly. As I was hanging up my bass, I noticed the static was still coming from the speaker even though there was no instrument or instrument cable connected to the head. This hum was not at a constant volume level or steady. It almost oscillating. The static was not constant. It was almost like the unit was picking up a signal or a hum from an outside source. The sound of the static reminded me of when you adjust the tone controls on older amps that have dirty contacts. My buddy threw in a speakON cable when I bought the head. I'm going to buy a new one today in hopes that it's simply a bad cable. I will also change out the power cable. It's worth noting, I use a good surge protector on my gear even though my home is newer and the power source has been proven to be clean. This has never happened with any of my other gear that has passed through my life. The only variables are the new head, speakOn cable and the power cable. Anyone ever experience this before? Any feedback is greatly appreciated.