All the amps you list are good and you won't have any problems - possibly apart from the Naim, I've seen poor reviews. Yamaha, NAD, Rotel, Denon all perform well.
Do not worry about ground loops if you don't have any ground loops - there is no real reason for concern. Almost all 'normal' hi-fi uses single-ended, RCA connections without any trouble. I'd never heard of balanced connections before I joined ASR and I never had ground problems. Perhaps I was lucky
Absolutely do not worry about the Wiim Ultra (or any other decent electronics) digitising any analogue input. The conversion is audibly transparent (you cannot hear any change) and then you get the benefits of DSP/Room correction which is huge.
You could just get the WiiM Amp Pro, which would be great in one box. You won't have any problems with the WiiM Ultra / Vibelink combination either. If you want to choose a different Amp ... also fine.
Spend more time thinking about your speakers. Those Kefs are probably much better than the QAcoustics and that's where the real differences are
Good luck