B&K Reference amps ... Opinions please

Hmmm... These amps get very little discussion, and I'd love to know why. I understand how they were marketed, one step up from products like NAD and such, but I'd like to hear more than just a general opinion if possible.... What were their strengths and weaknesses ? How would you catagorize their overall sound ? Do they have any strong inherant attributes ? I'm speaking of the Reference series, such as the EX4420 and such.
Thanks for your opinions.