I am surprised nobody has recommended a single driver speaker for your small space and low power amplification. High sensitivity is a perfect match with smaller space and low power. Some great choices such as:
Charney Audio (using Voxativ drivers)
Voxativ
Razz
Cube
Personally, I have a pair of Charney Maestros with Voxativ 2.6 drivers similar to your arrangement, an 8' equilateral triangle, driven by Airtight 300B amp (8 watts).
Outstanding sound. Replaced Wilson Sabrinas which are no slouch!