I have been looking for a good horn to mate up with my 399's I got from GPA. I really like the 1505 but they are rare and quite costly when you can find them. These will top off my A7 project so I want something appropriate. I know there are many to choose from.

Since I have a pair of 511B's I was wondering if anyone had adapted the large format drivers like the 399 to the smaller throat 511. I don't want to loose sonic performance. Is this something I should consider or should I use one of the large format horns. What would be a good choice for a home HiFi system. My room is approximately 19ft. X 22ft.
Thanks...