Hi I have just aquired a Beosound 5 complete with wall mounting and leads.  At this moment in time I caught between buying the beomaster5 and keeping  the unit or just selling it on.  Unfortunately before I am able to decide which way to go i need to ensure the unit is fully working,  is there a way to power up/test the unit without purchasing a beomaster 5 unit.

No, seems strange to get one without the other IMHO

Beosound 5 does not work without Beomaster/media 5. 

I don't think anybody would buy your BS5 unless for spares or they got the BM5 alone which is very rare.

So I would consider seriously buying the BM5 as well.