My only concern would be that the BX2s are thinner sounding than the old BR2s, particularly in the midrange. The BRs had a dose of midrange warmth that would counteract the slightly clinical Cambridge Audio sound, whereas the BX2s don't.
Auditioning will be the only way of being sure. Don't forget there are other talented speakers around in that price bracket. Of these I would suggest the Wharfedale Diamond 10.1s which I think would flatter the (excellent) 540A amp more.