@sigbergaudio comes to mind. Their
Inkognito 10 subwoofer is only a little over 6" deep(!) and the
Inkognito 12 is still under 7" deep(!!). In my opinion both are very well thought-out, and are optimized for this sort of application.
I thought about that, but the subs are just too expensive for my application. And they don't have a US presence at the moment. For an expensive item that is heavy and hard to ship, it makes it a tough choice. But I will say that I absolutely love the product from what I have seen, and I think it would work well in my application. I hope
@sigbergaudio does well.
I have customers who use two of the Swarm units as speaker stands, and I'm developing a version with a down-firing sub to keep the vibrations in the vertical plane. I also have customers who place one or two of their Swarm units atop a bookshelf, such that they don't take up any additional floor space. Not trying to talk you into risking a divorce! Just sayin' that their placement is pretty flexible.
It is hard to combine aesthetic considerations and to get great sound. I am trying to stay away from extra boxes in the room, and from speaker stands. Basically, I get the area around the TV (under and to the sides and behind the cabinet).
If I am being 100% honest, the cleanest approach is the DD 8C (as
@napilopez mentioned). They match the new media cabinet (black oak), I think they will handle low bass better than the Genelec 8351b (could be wrong here), and the tweeter is at the optimal height (the new media cabinet is 24" tall). I just have to get the digital signal into the speakers and I am done. I don't even need an electronics -- my TV will give me the 2.0 out (but I would have to convert either HDMI or Toslink to AES/EBU). But for a little over $12k, they are really expensive, possibly less reliable than Genelec, and may not hold their value in 5 years.
For the same budget, I can get 3x Genelec 8351b or 3x 8341a or 2x 8351b + 1x 8341a, but I need to solve the multichannel signal issue (maybe not terrible) and the speakers will be a little low (probably easy enough to tilt them up slightly), and they will blend a little worse with the decor (subjective). With Genelec, I can always sell them if it doesn't work out because they hold their value really well. That has always been one of my rules of audio purchasing -- buy something you can easily sell if it doesn't work out.
And there is KEF too -- the subs are the hassle there. Everything else is dead simple and clean.