If you like the sound of your system but just need a bit more bass control then you can add a power amp to the Mini as it has pre-outs.
If you are OK with second hand then the Quad 606 or 909 is a good start for a traditional class AB amp, or go for a newer Hypex Ncore class D amp from Nord acoustic. At a lower level the Topping PA5 is getting good reviews as well, there is a long thread on here from a guy that replace some pretty expensive amps with one of these.
Also, Arcam do tend to be slightly on the warmer side of neutral so that may be taming the B&W but I think the 606‘s aren’t as bright as the 607 going by reviews.
Forget what hifi reviews, 5 stars don't mean they sound better than a 3 or 4 star rated by a few individuals. Take them with a pinch of salt. Ive owned 5 star rated MA bronze 2 and 4 star rated much older MA Gold GR10, The Golds are better in every way.
My money would be on a pair of Mission LX3 mark 2, having owned a pair of the previous LX1 mark 1, Im confident the newer mark 2 will also be guaranteed to work well with the Arcam.