It can be a long time--I've seen reports of up to six months (try googling Shahinian speaker burn in to see some reports). But as an owner of Diapasons--and previously Obelisks---I think it's worth it in the end.
You don't say what's wrong with the sound, and I can't see your system, but another point to bear in mind is that the amplifier is critical---it needs to have high current and damping factor to control the drivers.
Finally, if your concerns persist I would call Vasken Shahinian and ask his advice directly. He's not always easy to get hold of, but he's very approachable when you do.
Best
David
You don't say what's wrong with the sound, and I can't see your system, but another point to bear in mind is that the amplifier is critical---it needs to have high current and damping factor to control the drivers.
Finally, if your concerns persist I would call Vasken Shahinian and ask his advice directly. He's not always easy to get hold of, but he's very approachable when you do.
Best
David