Is it even possible to set up a system in 12x12 room?

My system sits in a 10 x11 room. Look at my system thread. With the judicious application of room treatments and careful speaker placement...and naturally a near field listening position, I believe a great SQ can be had. I am VERY happy with my SQ. 

@paulcreed  In my room, my listening chair is placed against the back wall..with no detriment to the SQ. I have placed absorption panels on the back wall and do have a vault ceiling, which obviously helps. Listening in the near field should allow the speakers to totally disappear in the soundstage, I get tremendous precision of musicians on the stage..and plenty of depth. The hardest part about a small room is the bass response...which will require a lot of trial and error, and in my instance dual small subs. Nonetheless, IME you won’t get very deep bass regardless, although I have managed clean to 35hz.
One other thing you probably will not get is large scale...this seems to be a requirement to large floor standing speakers, which won’t work in these types of small rooms. Precision is the name of the game here, and something I would not want to trade for scale.

I don’t agree that in a small room speakers always have to be toed in. IME, that is not always the case, and in fact, in my room, I prefer the speakers to be placed straight ahead. (https://systems.audiogon.com/systems/4100) Experimentation is the name of the game here also. The design of the speaker has a lot to do with this aspect.
Also, I do believe that if the equilateral triangle placement can be accomplished, that is preferable.
Lastly, I think that getting the speaker more into the room and off the back wall is going to give you the most depth and imaging precision. Near field listening is the rule in this size of room, there really is no getting around that...which I actually believe is beneficial anyhow.
Rule of thumb...small rooms and small speakers...horses for courses.

@paulcreed   Cannot help you with home made acoustic treatments, they may or may not work? However, if you look at my system photo, you can get an idea as to how I have placed the room treatments. I also utilize a pair of the excellent Shakti Hallograph's. These tend to focus and extend the soundstage. 
Couch vs. chair...IF you have space in the room with all of the other gear, then I would say it probably doesn't matter. I use a chair, for the simple reason that it gives me more space and it allows me to sit a little higher.
I very much doubt that your new room will be any harder to set up than a 'normal' size room, whatever that is?? BTW, is this going to be a dedicated room..or are you also going to be putting in TV's, beds etc?

@paulcreed Sounds like you have a little work to do to get all of that gear into the room. The fact that it will be dedicated means that in all likelihood it should sound great!
Placing gear as low as possible can also pay dividends. Although having the LP12 on a wall mount is probably a good idea. I have mine on a center stand that is very massive ( yes I know that’s not what Linn likes) but I use a Tramp 2 and this seems to alleviate any issues with that. I also place the power supply on a separate lightweight shelf with Harmonix footers beneath it. The WTA arm replaced an Ekos 1 in my set up. It is FAR more transparent and resolving and a lot more precise across the frequency spectrum. The imaging jumped up a notch and the air around instruments was much better delineated. There was a minor loss in bass power but not in bass precision. Overall, a major increase in SQ. Having heard your previous set up with an Aro, I can say that the WTA is a far more precise and accurate sounding arm than the Aro. ( I never like a pivot point bearing on any arm, very easy to hear the chatter as it pivots off the point, IME) To that, I think that the very poor cabling that comes with the Linn arms and the Aro is a real detriment to the table. The Nordost Tyr that I use from the arm to the preamp is in a different league to the stock cables and connectors that come on the Naim and Linn arms. Odd that both Linn and Naim don’t seem to place much emphasis on this highly imperative aspect! Oh, set-up...that’s another thing. I am VERY lucky i have a set up wizard near me, no way i could attempt to set up the table, or the WTA by myself! The WTA is very difficult to set up...and not for the hobbyist like myself to consider! To that I have mounted a Lyra Kleos ( fabulous match) and the set up there needs to be ultra precise to get it to sing. Took my set up wizard hours and hours to do...if that tells you anything.

@paulcreed   Glad to hear that you are coming to grips with your small room. IMO, experimentation with speaker placement is beneficial...even in very minor amounts. I use a laser to get the accuracy needed. To that, i think a good general rule is the 1/3 application. 
Room acoustic treatments are definitely a major plus, and I think some bass trapping is always warranted.

Towed in is seemingly dependent on the speaker and the room. In my room, I slightly prefer straight ahead with my speakers, possibly not the case with different speakers. Again, experimentation is the key here.
Room acoustic treatments are possibly more important in a small room than big..again room and speaker dependent would be my experience.
I think there is no wrong or right about the small room set up, trial and error is the key, IME. BUT, once it locks in, you will know it...and the SQ should be excellent...with the proviso that very deep bass probably isn’t going to happen...and neither is large scale. These two aspects take a larger room and large speakers, BUT the off-set is greater intimacy and a more resolved sound in many cases. Near-field listening, again IME, is in many ways beneficial than to listening to music from some distance..in many instances too far due to the size of the room.IMHO.