Got mine yesterday and like someone else mentioned; when you turn it on, it very harshly POPS your headphones. Disconnecting mine each time I turn it on now.
Lu_eThere is no muting / delay timer on these amps, so defo unplug your headphones before you switch it on/off .
Furthermore, it's best to wait a minute or so before you plug your headphones.
This is to let the tubes warm up a bit, it takes about 10 secs until they start producing sound.