I have a KingRex UD-01 Pro DAC, so probably not many are familiar with how it sounds. But it has a big sound, and I've always felt that the NAD compresses it a bit. More breathing space is required.
The main problem is that the room is 25sq metres and the Wharfedale 9.1s small. While I enjoy the sound of the NAD, I think something with extra punch that gives more space around the instruments and air is needed. The Rotel would also give the option to add a power amp at a later stage.
I was also thinking about the possibility of upgrading to the Wharfedale 121s with the Rotel for a warmer presentation, but even while the 9.1s are a bit neutral for my tastes, they're so good in every other respect, I'm wary of giving them up. The reviews of the 121s seem very mixed.
Unfortuntely, there isn't much chance for auditioning. Although I do have the option to send back after two weeks if I don't like what I hear.
Max budget for the amp is £350.