PGA2311 pre-amp static discharge problem

Hello AoS members, I have a PGA2311 based pre-amp like this one on eBay.

Works very well and sounds good but is extremely sensitive to static discharge which causes the pre-amp to "crash" and make the most appalling speaker destroying loud noise. It's like hum and buzz at full volume.

The "crash" can be triggered occasionally simply by touching the volume knob and more frequently by the static discharge from vinyl LP's :scratch:

I've tried earthing the case but it hasn't made any difference.

Any suggestions to fix this problem are most welcome!!

Cheers