I have experienced a bit of bad luck. Six hours into the burn in, just playing music through the system while the headphones were sitting on my desk the system died. Suddenly no sound from either driver only static. I shut down the system and disconnected the hp's. I shorted the pins with my finger to discharge the hp's. A few minutes later I reconnected everything and it played music but the left channel was down maybe 10-12db. I used the balance on the volume knob to get it balanced but it required too much movement and the left channel was distorting. I shut it down and came back to it hours later. This time it seemed ok but soon the volume in both channels was reduced and the channel imbalance returned. If I tapped on the left ear speaker I could hear it momentarily get loud for an instant then die. I boxed up the system and I will return it to the dealer today. A very long drive for me to resolve this. I do not have another Stax system to determine if it is the hp's or the amp at fault. I believe this is referred to as infant mortality.
I sympathize, the left channel on my GES is intermittent, not tube or cable related. I'm sending it back and trading up to the WES, though. So it's all good.