[FLCL]

The right channel suddenly died out of no where, and the left channel only barely comes in if the gain switch is off(when it's on it dies). It sounds like your car radio does when it is between 2 stations that are fighting each other and one is a talk show and one is music with some static thrown in. Also noticed when I turn on the amp (after the initial click/pop) there is a strange low hissing/buzz sound that goes from the right channel, fades, then to the left, and fades.

Think the headphone jack came completely loose or a more serious issue?

 

[HiFlight]

Is this when powered by USB or battery?   I assume you have replaced the battery.  It sounds like a dying battery.  Is there a chance that you have rolled an opamp rated for 5v at some time in the past and then recently selected battery power instead of USB power?   That will also result in the symptoms you describe.