The first one I ordered arrived perfectly externally. But I starting noticing there was a rattling sound coming from inside it when I moved the amp. I suspect there was something loose. The second one did not have this problem, but one of the charging indicator lights was going it, it was only half lit. The third one I didn't even bother trying, I returned it immedietly because the packaging was all beat up with one of the corners of the item's box smashed in, even the plastic seal wrap had been ripped open from the abuse it had taken. The fourth one, which I'm returning soon, arrived fine except that it had a small scratch on the metal of the back of the amp, besides this the volume knob was extremely loose, unlike the previous ones, this resulted in accidental volume change quite often.
My conclusion is that this 'Batch' (along with their other current stock) was all sent to the Amazon Fuffilment center in the US from Cayin in Hong Kong. But on the way to the U.S, they were mistreated or got damaged from miscare. That would explain why they sustained damaged that could only occur from shock. Except that one with the smashed in box, that one looked like a fridge fell on it.