I've worked out what was causing the low battery issue, though I don't understand why it caused it.

I have Hijack installed, not a particularly recent version. I have been using the Hijack screen blanking functionality, set to turn the screen off and examining 95% of the screen. I was using this in one of Mark's docks.

The Hijack timeout was set to 15 seconds, just about the length of time that the empeg was surviving for before dying.

When I disable the Hijack screen blanker the problem goes away. The player no longer suffers with the low battery turn off. Yippee !

What I don't understand is why it caused this to happen. I know that the amp remote line is turned off when the empeg screen is turned off, but I don't see why this would kick the empeg into a low battery state ?

Right, next step, get the tuner working...