The Airport Express connection was interesting. I had the music in uncompressed AIFF files on a harddisk, and sent it to the Airport Express via wireless. The Express has optical digital out (Toslink). I converted that to S/PDIF and piped it to the BL5s. That meant I had an unbroken digital delivery from source to speakers. And I could tweak the signal before transmission from my computer using the Equalizer built into iTunes.

Could of course also use the computer as a CD player with this setup - it pulled the music right off the CD, in digital format, and sent it on as such to the Airport Express without using the computer's DAC.
 

@soundproof what's the reason for tweaking the signal?

Hi,

 we are installing a pair of Beolab5's at a customer's house but are not using a beosystem.  The problem we have is that the Beolab5's are the front L and R speaker in a surround setup on a different processor and the other speakers are built into the ceilings.

 We have a couple of options (we have set them up as option 1 by the way):

1.) We could just program the crestron to issue an on command and then do a 10 second burst of volume up to syncronise the volume levels (by having them both flat out).

2.) If someone here were to provide us some information about the sync link cable we could directly write to that to control the volume.

 Option 1 is a bit hissy, not too bad, but not ideal.  Because the volume has to be set every time they are powered on, it would nearly be impossible to set the an accurate calibrated level by IR as it is relative - so the only absolute setpoint is max (and min as well, but that is useless to us...)

Option 2 is far preferred as the sync cable is obviously working in absolute gain level (as opposed to relative).  We really need some info on how this cable works.  E.g.:  Analog Voltage or Digital Serial.

If you know anything we would be extremely appreciative.  Specifics would be even more helpful.  For example, if it is digital, baudrate 9600N1 etc

 Many Thanks,
James.