Just had my car nicked at the weekend, I was due to install my amp and empeg this week, so its a good thing I hadnt...
They wrote it off unfortunately.

I had a Home Cinema sub in the boot with an invertor powering it.
The insurance company claimed that it wasnt car audio equipment and so we had a nice long arguement about it and they finally caved.
This starts to make me think about what they would say if I tried to explain what the empeg is all about...

Anyway, your best bet is to check out MAX Power et al, as they are bound to have adverts for it. I know you can get a separate policy for it and with an amp, speakers and empeg its going to be more than £500 worth.

On another note are you sure about your excess? Mine is £400 but only if I toast the car. The theft and write off is only a £100 excess.