Due to the influence of COVIC-19, delivery will still take some time. We conducted an operation test immediately after receiving the product. There is a slight pop noise when the power is turned on and off, but this is not a problem. There are no volume gang errors. Tested with a 24V / 30V power supply, the sound is very powerful and well made. The only dissatisfaction is that the LED on the front panel BT connection indicator violently flicker with red <> green. It is a very disturbing specification to use. I want you to improve.