Strange offset behavior

[Disco-Pete]

I hope someone can give me some insight as to what could be causing this odd behavior in my Citation XX. Without a load, offset is around 65mv both channels. After I zero the offset and hook up the speakers, it jumps back up to -68. However I can zero the offset with the load connected. But if I disconnect the speakers, it jumps back up to 65mv. Weird. I've never seen this before. On any other amp, it's always stable at the reading no matter what. I'm wondering if there could be imminent disaster about to happen. Is this potentially a serious issue? TIA

 

[JonSnell Electronic]

I would look at the output with an oscilloscope. It is probably unstable and oscillating, with/without a load, at HF.

 

[Disco-Pete]

Thank you. I take it that means I should not use it til it's corrected. Where to look?