Correct me if I'm wrong Dave, but isn't the sync cable there to also syncronise the word clocks when using the analog inputs - meaning it's not strictly necessary to get the best out of the speakers when using the digital inputs as the word clocks will automatically lock on to the source?

Thanks, Dave. You wrote " I've never been confident about the sync cable, and I use non-B&O gear." -- and that had me wondering whether you felt the sync cables weren't doing what they are supposed to do.

Very happy with my sync-enabled speakers!

Soundproof

Do you have original B&O synch cables? I have some made up custom and they have been tested, but if they are somehow reversed ends they would not work. Do you know anything about the composition of the cables?

I first got a standard non-B&O cable, with the correct minijack plugs, but got no connection. Then I ordered the B&O ones, plugged them in, and everything worked as it should.
My only reference for the cables having been reversed (plus from one plug to minus on the other plug) was a comment here, in another thread - I do not know whether this is actually the case. Though my experience with the two cables seems to indicate that something is different in B&O land ...

Mystery solved. I pulled out a soldering iron and made my synch cable a crossover cable (ie red goes to white and white goes to red). Now everything works perfectly. 

Lesson: The B&O synch cable is not standard. It is not complicated to make its just not standard.

Thank you everyone for all the ideas and help. Soundproof your last comment was the clue that solved the mystery

Didn't you tell us you had the right cable?

Congratulations, phult. Now, after having tried every which way, did you have the peace of mind to notice any change in the sound, pre & post sync cable?

Hi Guys,

Thank you for a very informative discussion!  I have updated my comments on the configuration of the sync cable to avoid causing any confusion to future readers of the thread.

For reference, if you choose to pre-set a pair of 'Lab 5's to maximum volume and use a non-B&O analgoue source to control the volume, there should not normally be an audible background hiss present, unless you listen closely with an ear to the tweeter lenses.  Audible hissing would suggest either a poor quality source component, or an impedance mis-match at the line input socket (this can happen where a pre-amplified headphone output is connected to a line input).  Hope this helps,

Steve.

I have not noticed any difference in sound. Before and after they both sound great.

I think the question being asked is does the synch cable only control volume, power on/off, or does it somehow control any of the DA converters word clock. To this I have no idea.

thanks once again for all the help

p