Ian and Eric are pros at this stuff and always offer "sound" advice. Although I'm not a fan of subwoofers (good systems don't need 'em imo), I'd reconsider my options and look at a couple of small "cubes" and a small sub. I've still got big ole 170lb vintage Polk towers, but have had a cube/sub (slightly larger than a shoebox) system on my "desktop audio PC" for years...surprisingly good sound for what it is. Now ask the pros about suggestions
edited: ps: If you're set on in-wall and don't want cubes, just plan on a small sub to provide the low end...