Thanks everyone.
I tested the fuses on the 7 and they are indeed blown. According to Glenn it will be fine when they’re replaced.
He says I should give the RIAA a 30 second head start. In my opinion that means it should have a relay circuit like the 25 does. He says he can fit one so I’ll look into that.
This isn’t a HiFi system I want my friends and family to be scared of breaking so some added protection will help.