I agree with Carlito. If you want to add a Beomaster, get a BM7000 or 6500 and a BG CD7000 (if you want to listen to CD).
The CD7000 is a superb machine with a direct spdif output, that can be activated by pressing CD on your Beoremote.
Sounds better than BS9000 connected via spdif (don`t ask me why, but it`s noticable).
Get fully wired Powerlink cables. Set your BL5s to L.OPT 0.
Now the BL5s will be controlled via Powerlink through your Beomaster. If you select CD, the CD input of your BM will be opened and the BL5s will check for digital signal. Volume level and Power on/off will also be controlled (in sync) via Powerlink.
Even an MCL2 AV should work as an audiomaster. It`s a little white box (to be hidden away) with three DIN inputs, A.MEM - CD/PHONO - AUX/TV if I remember correctly. You have to connect a separate IR receiver and a 15V psu. Works like a Beomaster, no additional master necessary.
And it is cheap...
Hope this helps
Stefan