Well, this is a frustrating old topic! Haven't been able to replace the standard audio with an aftermarket one, despite there being a huge number of potential candidates, as Subaru saw fit to make the audio, the nav unit and the climate control all part of the same set-up. The CD player is only offering me "Error 99", so I can't use that. Subaru UK is a rubbish organisation when it comes to support for its older models, it has to be said!