Hi,
I'm sorry to hear that you have such an unsupportive dealer. You should write that directly to B&O!
Do I understand you correct that you use an Equalizer on highend speakers like the Beolab 5?
In my opinion these are speakers that are intended to listen to as they sound - without any external correction.
Do you use "Loudness" etc, too? Perhaps that's the problem with the speakers!
With equalizer and loudness you can damage nearly every speaker when you crank up the volume too much!
They are not a horn construction and I can imagine that the equalizer and/or loudness etc. disturbs the speaker because they adjust themselfes to the room automaticaly with their integrated microphones.
Now the internal computer of the Beolab 5 thinks, "Ok, I'm done." - and after this you feed him with an equalized signal and it can't adjust itself anymore.
Try to set up every sound setting to "zero" (as you should always do for enjoying music with highend speakers!). No adjustment to high, low, loudness and external EQ like from the Mac. Adjust the TV the same.
Now you should let the speaker adjust themselves again. After adjustment: Test them, listen to them. How do they sound without adjusting the sound? Can you now "crank the volume up"?.
Perhaps you already damaged them, than you could hear some internal noises from the speakers that don't belong to music.
As english is a foreign language for me, I hope my point is understandable!?