Those are probably quite good. In addition to my 11.4, I spent some time listening to the bookshelf 11.2 which is 2-way like the 11.3 model. Those also had a pleasant sound from any spot or angle. Power...I doubt they need an unusual amount of power. Sensitivity is above average:diamond 11.3
https://www.stereophile.com/content/wharfedale-diamond-112-loudspeaker-measurements
There are not many amps with significantly more power in stereo than my AVR-2312Ci (it's only running two channel right now). You'd need an amp with like 300+ watts at FOUR ohms due to the logarithmic nature of hearing and the complex nature of loudspeaker impedance. We swapped out that -2312 for currently a ATI 525NC (300W @ 4 ohms) but it seems the -2312 had enough power even though the Focal 936/CC900/SR900 setup represent difficult loads.