Thanks for your reply!

I just did a search at the 'high efficiency' forum that hit a message from Bruce Edgar (see below) that may be the one you refer to - at least it corresponds quite well with your memory!

http://www.audioasylum.com/forums/HUG/messages/24987.html

(I hope it's o.k. to refer to other peoples post in this way - if not please let me know)

Here Bruce Edgar claims that only misalignments larger than 1 foot can be heard and primarily at higher frequences.

In a related post Bruce Edgar states that using 1. order crossovers minimizes the errors even further.

Have you any idea whether 4th. order crossovers would makes potential alignment problems worse - and if yes why?

Regards
Peter K.