Sounds like that amp is always on... I doubt that the green LED should always be on - most amps (can't comment on you specific one as I've never even seen one) will use that as an indicator that the amp is on - and that would/should only happen as the amp remote turn on wire is high.

Try disconnecting the remote wire from the amp, plug in the empeg and see if you get sound out of the speaker attached to it. If so, then it's on without a remote connection...
That most likely points to a broken amp turn on circuitry inside the amp...

/Michael