Interesting thread. I would say that there are basically two ways to deal with a problematic room (but aren't they all problematic, to some degree?). First is by passive or active treatment. The former is classic room treatments, as little or as much as is needed. The second are active crossover networks and/or DSP, which includes source-based correction such as Dirac and others.
Second, you can minimize speaker/room interactions by using speakers with omnidirectional or dipolar designs. These may not overcome all the problems with your room but there are other advantages to these designs; namely soundstage and imaging. mapman mentioned Ohm Walsh speakers and alymere mentioned Linkwitz, both good solutions. I sold the Larsen line for several years and setup several pairs in absolutely dreadful rooms, mostly to the satisfaction of the buyer.
Myself, I have happily rediscovered Shahinian's great Obelisk speakers for my difficult living room and I love them, although they did necessitate a change from tube amplification to SS. But they do sound great!
Second, you can minimize speaker/room interactions by using speakers with omnidirectional or dipolar designs. These may not overcome all the problems with your room but there are other advantages to these designs; namely soundstage and imaging. mapman mentioned Ohm Walsh speakers and alymere mentioned Linkwitz, both good solutions. I sold the Larsen line for several years and setup several pairs in absolutely dreadful rooms, mostly to the satisfaction of the buyer.
Myself, I have happily rediscovered Shahinian's great Obelisk speakers for my difficult living room and I love them, although they did necessitate a change from tube amplification to SS. But they do sound great!