This integrated amp has developed a problem I'm hoping someone here can shed light on. One channel is inactive after powered on until the volume is turned up to about 30-40%, when it will "kick on." After that it's usually fine.
Plug in a set of headphones and play some music. If the same problem happens then I'd suspect a bad volume control potentiometer as a first item to check out. It may be fixed with a quality contact cleaner or it may need replaced.
or the speaker relay contacts are oxidized, and begin conducting after you reach enough voltage to break down the oxide layer. this can happen from age, or from too many times turning the amp off while the volume is still turned up. that creates a small spark as the contacts open, and the heat from the spark oxidizes some of the metal on the face off the contact.