combo acoustic treatment ideas - who's tried some?

Hi everyone, Anyone here had any experience in acoustic treatment combos? I've been mulling over getting the most amount of treatment out of a smallish control room back wall and have been wondering if it'd be efficient to try and cover a few different bases where it's most efficient to do so. The first example I have been toying with is a QRD diffuser in front of a hermholtz style trap. You've got slots either side of the QRD and the whole thing lives in a sealed box. This would likely be hard to predict I would guess, but efficient because you're not wasting space at the front of a hermholtz. Second example was placing membrane absorbers on the back wall boundary where they are most efficient behind existing broadband trapping. Double wammy? I figure you get the most out of your broadband off the back wall and you get the most from your membrane's on the wall so why not let each work at their most efficient. Anyone tried any of these or others?

Here's a few examples of I found in some of John Sayers' studios. This looks like a diffusor slot resonator combo: This looks like a combo monitor soffit/slot resonator I've seen this in a few of John's designs. I wonder if the slots are detrimental to the extension of the speaker as an infinite baffle?

Of course many have tried many things. I am dubious about diffusors in small rooms, but scattering should be fine. Check out the work of Boggy, Bogic Petrovic, sadly RIP. Pics on Instagram. Google MyRoom. A guy on a FaceCloth Acoustics group did a fabulous small room using EPA/VPR LF trapping (Steel Membrane embedded in 200mm fibre) and DIY BAD panels. What size is your room and what are the boundaries made of?

Thanks Dan, My room is tiny, tiny and I'm turning it into a vocal booth for my wife that will stretch as an edit room for her and a music production room for me after hours. http://www.johnlsayers.com/phpBB2/viewtopic.php?f=1&t=22260 2695 long, 2265 wide (bare frame) and ceiling height is currently 2400, but I'm planning on ripping that out this week and building a frame above the current ceiling line to house a bunch of mineral wool. Thanks for the heads up on the MyRoom acoustic design, i've been through the rabbit hole with that the last week reading as much as I could find on it. I really like the concept. Obviously I'm a lot smaller than any of the rooms it's worked for, but I may even experiment with one of those diffusors across my back wall tuned high enough so that I'm not right in the funky zone for it.