I honestly thought it was non techy head that was at fault - but reading some of these comments restores my sanity.

I think I've got such a simple set up - just a speaker, turntable and port.  Every time I want to switch between radio to turntable I have to do a minimum of 3 steps and check that the port is still ticked, get Line-in etc. 

I feel like I should just shout at the speaker 'the turntables on' .  It shouldn't be this hard.