I want it to be anechoic for 2 reasons. First, it gives the most realistic and detailed soundstage / depth there is with the right music. Truly like being there except you have an additional "magnifying glass" by turning up the volume. It's a very special sound. Like a headphone except many times better in fidelity and not inside your head but instead with perfect head related transfer function so sounds can be heard to be almost against your head to hundreds of meters away. It's really an experience in and of itself, not anything like a speaker in a room and not anything like a headphone.
Second reason is, because you hear everything and the sound is completely flat in frequency response at your ear (or with any curve you choose) it allows to make / mix / master music very well. I've spent the past 12 years doing full time research in music theory (how our brains handle the tonal side of music) and have now finished this. I still have to write a book and publish etc but taking a well deserved break before doing this, and this is my break
Still somewhat usefull as I want to produce some music based on some new possibilities given by my reasearch (like correctly harmonized "microtones" like those found in traditional makam music). Want to make it on a high resolution soundsystem and it doesn't get more high resolution than in an anechoic environment.
I had such a room before, but with a few errors. Though we learn from the mistakes.
I thought it wasn't possible to make such a room in my current house. Was fantasizing about building such a room in the future when I got the realization that a version that should work wel is indeed possible in my room. That was a few days before I started this thread
And yes that was my initial though. That in such a room off-axis does not matter. But my experience with several Klein+Hummel monitors in my previous room made me a bit scared. They gave me trouble around the crossover. I then thought the window for truly in phase crossover on-axis is so small you'll have to put your head in a vice grip. So I started thinking about proper crossover behavior and making the listening window wide enough. Perhaps I've gone a bit overboard with this though.. And perhaps more of the trouble I heard before was more due to a ground reflection (which I know was bothering me a lot in my previous room, it was semi anechoic half a meter thick glasswool with space behind everywhere with only the floor not treated, but that was one bad sounding floor it was thick plasterboard with floorheating and it vibrated and gave a strong relfection.. so audible in those listening circumstances).
Still making the crossover sim examples (got distracted a bit) and I'll know after I made them which angle is still acceptable to me. As long as I can move my head in a 20cm vertical window without any SQ loss (I really don't want to hear any phasing in that window at all) I'm actually happy enough perhaps..