> one is for audio output to an Amp

We use RCA (phono) jacks which are the defacto standard. Even if your Blaupunkt uses something else it won't be a nightmare to chop it off and replace with RCA's when you change to an empeg.

> one is for speaker output

This becomes redundant

> the remaining one connects to the battery, lights, phone etc

This is PROBABLY an ISO connector, which the Mark 2 has fitted as standard. It provides constant and switched power, ground, mobile phone mute and headlight dimming signal all on one connector.

So in summary, if you get an amplifier working well with your Blaupunkt, switching to a Mark 2 empeg should be easy.

Rob