So with that microwave vent and that other smaller flex duct, should I insulate and close the bottom of the bay up or build a tighter soffit just around the duct and vent?
Do the easier thing: insulate and close off the entire stud bay. Much easier!
Or am I just be silly because the NS10s aren't known for their bass response anyway?...

To my way of thinking, the purpose of having NS10's is so you can hear what the mix will sound like on a pair of typical low quality home stereo speakers or car speakers, that are set up poorly in a typical living room....

Now some folks might get upset with my view, but to me that's what I use them for. So I wouldn't be too concerned about having the NS10s set up "perfectly", when that isn't really their purpose.
then I read a post by John saying people are really over complicating the matter. Build a big solid baffle and secure your speakers behind them...
Have you seen this post by John, on the 3 (or 4) ways you can soffit-mount speakers?
http://www.johnlsayers.com/phpBB2/viewt ... &start=197
Did you remove your amps?
I always suggest doing that, as YOU WILL need to tweak those settings many times during the final room tuning, and pulling the speakers out to do that each time is a pain in the rear end! so pull them, extend the wiring, and mount them on the front/side of the soffit, or on a bracket, or some such. And of course, replace the rear panel on the speaker box with a similar piece of wood!
Do I build the inner leaf with the double 5/8s drywall all around and THEN frame and build another front wall with the soffits and middle section.
Yup!
Do the soffits need to be sealed or are they open to the drywall with just some insulation in them?
They don't need to be sealed: after all, there's a huge ventilation path running through them, to cool the speaker, so sealing the rest doesn't help at all.
Also, I did some tweaking of my RFZ design and finally got the angles worked out correctly
Looks good!
I am still on the fence as to whether angle the ceiling or add a cloud. I have to angle the ceiling anyway because of the HVAC soffit that has to be built but the degree to which I do it depends on if I go the cloud route or not .
Either way will work, but if you have good ceiling height then a cloud can add a really nice touch, both acoustically and visually. But if your ceiling is low to start with, then a cloud is probably out of the question.
My original plan was to splay the walls to create my RFZ, then I thought maybe slot walls would be better? After many many many hours of research it seems that it doesn't really matter which method I choose as long as either one is done correctly ie, angles right for splaying or enough absorption implemented correctly for the slot walls...
Right! But to be honest, I prefer to have those walls solid and use slots further back in the room. Slots are tuned devices, so they can change the overall perception of sound in the room, and you don't want that happening too close to your ears.
- Stuart -