Decoud,

I would prefer to discourage you but it is certainly up to you what to do. My motivations are following:

1)      If you wish to explore Milq then you do need over 100dB sensitively but it is not a good idea to build an unknown to you acoustic system of a new for you topology in context of which you would learn what an amp might do.

2)      If your new acoustic system be a horn, and if you are new to horns then I would defiantly shell to stay with amplification the you know already and that you feel comfortable with, unless your current amps can’t driver horns.

3)      There is no acoustic system requirements know to me that is needed to be used with Milq. You need high sensitively and you need an acoustic system that more or less truthfully handles harmonic content of Sound as Milq has tendency to demonstrate it’s might in context of proper Sound.

4)      The idea of single horn speaker is fundamentally contradict, in my view, the concept of horn-loading. There are some people out there who use horns with 6”-15” throat with those horns so-called full-range drivers. You might consult with http://fullrangedriver.com and many others who take this direction. I do like it and I do not call it “true” horns but rather “the drivers with leaves”

Sorry, I am not helpful in your project, but others might provide more “desirable” response.

Decoud,

There is a lot of information on the subject of architectural horn design on this site. I would advise you to read older posts, use search. You might start from this one:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=6816

I do not see anything crude in what you are trying to do. If you want to test the building method then I personally would go for smaller horns perhaps…

What I am against in what you say that you associate your projects of horns installation buildings with amplifier design, would it be mine or any other. I would advise to you if you wish to build a 4-ways horn system then do so.  Use your 845-based SET to drive them and get good sound from your new acoustic systems. Then assess what specifically you feel is wrong or insufficient in the Sound that you get. If you conclude that the specific problems that you will identify were on the responsibility of amplification then you might try other SET, including my Melquiades. 

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=432

This, from my point of view, is the right way to approach the subject. I would not use an amp as a tool to cure the potential problems of experimental acoustic system.