Amp tripping circuit breaker.

I have a 20 amp circuit, AFCI breaker, with only my entertainment rack on it.  The breaker has been tripping periodically for about a year now.  Recently the problem has been worse and I suspected my amplifier.  Long story short, the breaker only trips when the amp is plugged in, with statistical certainty.  Unknown if it matters if amp is on or not.

Amp is a Monolith 7.  I opened the cover and saw no obvious signs of damage.  Everything is clean and dust free.

any thoughts?