I believe Zu offers a trial period of 30 or, maybe even 60 days. This, and the fact that the Definition speakers are held in such high regard right now, would sway me into giving them a try. Indeed, they sound like special speakers from what I have read. It would really be great VS, or their dealers offered a similar audition policy. It's worth checking on since virtually all credible dealers provide an audition-at-home policy. The potential issue I see with this is that the DB99 may not be stocked. Therefore it will be difficult to auditon it unless VS provides an audition policy.
Verdict: If you can't listen to VS, go with the Zu's. You can always return them should they do not meet your fancy. But, I really don't think you will return them once the disk starts spinning.
Verdict: If you can't listen to VS, go with the Zu's. You can always return them should they do not meet your fancy. But, I really don't think you will return them once the disk starts spinning.